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  • Is this a valid css?

    - by Pandiya Chendur
    I have a pager in my page with anchors in it... I use the following css... .page-numbers a { color:#808185; cursor:pointer; text-decoration:none;outline:none; } .page-numbers a:hover { text-decoration:underline; } .page-numbers a:visited { color:#808185;outline:none; } But my anchor tag doesn't seem to take the css above instead it uses the css below, a { color:#0077CC; cursor:pointer; text-decoration:none;outline:none; } a:hover { text-decoration:underline; } a:visited { color:#4A6B82;outline:none; } Which i have given in the top of my stylesheet... Any suggestion...

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  • JQuery object expected error when accessing page via url routing.

    - by Andy Evans
    In my global.asax I have url routing setup like below: routes.MapPageRoute("User Logon", "{Vendor}/Logon", "~/Logon.aspx"); In the logon.aspx page, I have a script that "stylizes" the logon button: <link href="jquery/css/flick/jquery-ui-1.8.1.custom.css" rel="stylesheet" type="text/css" /> <link href="images/style.css" rel="stylesheet" type="text/css" /> <script src="jquery/js/jquery-1.4.2.min.js" type="text/javascript"></script> <script src="jquery/js/jquery-ui-1.8.1.custom.min.js" type="text/javascript"></script> <script type="text/javascript"> $(document).ready(function () { $('#<%= ButtonLogon.ClientID %>').button(); }); </script> When I access the page us a url (in debug mode) http://localhost/logon.aspx?v=1 the page loads correctly and the jquery button command loads correctly. But then I access the page using the new url route, I get this error. Microsoft JScript runtime error: Object expected Anyone have an idea why this occurs? Thanks.

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  • Search in multiple xml files

    - by Ram
    I have a windows Xp Sp2 system where the windows explorer search is not able to find the text in xml files. Is there some setting that enable the search in xml files? It finds in text in text / doc files in the same folder.

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  • How can i get HWND of external application's listview? In Windows Api using c++

    - by Marko29
    So i am trying to make app to get content of my explorer listviews and get item text etc.. from it but here are the problems... If i inspect windows explorer folder(using spy++) with listview, just for testing purposes i will use random folder. It shows me that caption of the window is "FolderView" with class "SysListView32" and the top level window where this listview is nested is called "reference", this is also the title of windows explorer folder where all the files are. So what i do is.. HWND hWndLV = FindWindow(NULL, TEXT("reference")); // first i get hwnd of the main window, this is where listview window is also nested according to spy++, thats why i do this first. HWND child = FindWindowEx(hWndLV, NULL,NULL,TEXT("FolderView")); // trying to get hwnd of the listview here but it fails, same happens if i also put the class name along as HWND child = FindWindowEx(hWndLV, NULL,TEXT("SysListView32"),TEXT("FolderView")); I am using bool test = IsWindow(child); to test for fail, also VS debugger shows 0x0000000000 each time so i am sure i am reading results well. So i am stuck on this probably simple thing for most of people:( p.s. i am on vista64(if that matters anyhow) edit: It appears that this function works only if i search the first nested level of a parent window i am searching. So i assume what i need is a way to get handle with some sort of deep nested level search. I also tried to go step by step by defining hwnd of every parent then i use findwindowex on it but oh boy then i get to the point where there are 5 nested windows all with the same name and only one of them contains my listview, so nice uh?

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  • css, jquery issue

    - by wadada
    I was playing with Infogrid on my site. I added a header, a footer and added some text on the last block of iron man. As you can see the footer doesn't show up and the text of the last block is cut off. Now if you remove overflow:hidden; on the body, html the footer shows up but the text is still cut off. Any idea on how this the footer could show up without the scrollbar (so overflow:hidden; has to stay) and how to get the text of the last block to show up entirely? Thanks in advance and have fun :) wadada

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  • How do I display a jquery dialog box before the entire page is loaded?

    - by obarshay
    On my site a number of operations can take a long time to complete. When I know a page will take a while to load, I would like to display a progress indicator while the page is loading. Ideally I would like to say something along the lines of: $("#dialog").show("progress.php"); and have that overlay on top of the page that is being loaded (disappearing after the operation is completed). Coding the progress bar and displaying progress is not an issue, the issue is getting a progress indicator to pop up WHILE the page is being loaded. I have been trying to use JQuery's dialogs for this but they only appear after the page is already loaded. This has to be a common problem but I am not familiar enough with JavaScript to know the best way to do this. Here's simple example to illustrate the problem. The code below fails to display the dialog box before the 20 second pause is up. I have tried in Chrome and Firefox. In fact I don't even see the "Please Wait..." text. Here's the code I am using: <html> <head> <link type="text/css" href="http://jqueryui.com/latest/themes/base/ui.all.css" rel="stylesheet" /> <script type="text/javascript" src="http://jqueryui.com/latest/jquery-1.3.2.js"></script> <script type="text/javascript" src="http://jqueryui.com/latest/ui/ui.core.js"></script> <script type="text/javascript" src="http://jqueryui.com/latest/ui/ui.dialog.js"></script> </head> <body> <div id="please-wait">My Dialog</div> <script type="text/javascript"> $("#please-wait").dialog(); </script> <?php flush(); echo "Waiting..."; sleep(20); ?> </body> </html>

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  • CSS: move a "float:right" element to top (to align with the first element of the list)

    - by Patrick
    hi, I've a sequence of elements and the last one has css "float:left". I would like to display it at the same height of the first element and not on the bottom of the list. (I cannot change the html code, so it is the last in the list). At the same time, I would like to keep it on the right. How can I make it wich CSS ? thanks Code: <div class="field field-type-text field-field-year"> <div class="field-items"> <div class="field-item odd"> <div class="field-label-inline-first"> Year:&nbsp;</div> 2009 </div> </div> </div> <div class="field field-type-text field-field-where"> <div class="field-items"> <div class="field-item odd"> <div class="field-label-inline-first"> Where:&nbsp;</div> Musée Rath, Geneva </div> </div> </div> <div class="field field-type-text field-field-when"> <div class="field-items"> <div class="field-item odd"> <div class="field-label-inline-first"> When:&nbsp;</div> 25.8 – 27.9.2009 </div> </div> </div> <div class="field field-type-text field-field-editor"> <div class="field-items"> <div class="field-item odd"> <div class="field-label-inline-first"> Editor:&nbsp;</div> Blabla Blabla </div> </div> </div> <div class="field field-type-text field-field-material"> <div class="field-items"> <div class="field-item odd"> <div class="field-label-inline-first"> Material/techniques:&nbsp;</div> contemporary art installations </div> </div> </div> <div class="field field-type-text field-field-dimension"> <div class="field-items"> <div class="field-item odd"> <div class="field-label-inline-first"> Dimension:&nbsp;</div> 2 floors in a neoclassical building </div> </div> </div> <div class="field field-type-text field-field-artists"> <div class="field-items"> <div class="field-item odd"> <div class="field-label-inline-first"> Artists:&nbsp;</div> Blablablabla balbalbalbalba </div> </div> </div> .field-field-year, .field-field-where, .field-field-when, .field-field-editor, .field-field-material, .field-field-dimension { width:300px; } .field-field-artists { width:400px; float:right; clear:right; top-margin: -200px; }

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  • How to accurately resize nested elements with ems and font-size percentage?

    - by moonDogDog
    I have a carousel with textboxes for each image, and my client (who knows nothing about HTML) edits the textboxes using a WYSIWYG text editor. The resulting output is akin to your worst nightmares; something like: <div class="carousel-text-container"> <span style="font-size:18pt;"> <span style="font-weight:bold;"> Lorem <span style="font-size:15pt:">Dolor</span> </span> Ipsum <span style="font-size:19pt;"><span>&nbsp;<span>Sit</span>Amet</span> </span> </div> This site has to be displayed at 3 different sizes to accomodate smaller monitors, so I have been using CSS media queries to resize the site. Now I am having trouble resizing the text inside the textbox correctly. I have tried using jQuery.css to get the font size of each element in px, and then convert it to em. Then, by setting a font-size:x% sort of declaration on .carousel-text-container, I hoped that that would resize everything properly. Unfortunately, there seems to be a recursive nature with how font-size is applied in ems. That is, .example is not resized properly in the following because its parent is also influencing it <span style="font-size:2em;"> Something <span class="example" style="font-size:1.5em;">Else</span> </span> How can I resize everything reliably and precisely such I can achieve a true percentage of my original font size, margin, padding, line-height, etc. for all the children of .carousel-text-container?

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  • Binding key/value pairs loaded from xml

    - by Hichem
    I want to load key/values configuration pairs stored in XML file. To bind a collection of data i know i need to use the ArrayList class, but the problem is that i want to be able to bind the loaded values using their corresponding keys and not by their indexes in the ArrayList object. For example i want to be able to do this : <mx:Text id="errorText" text="{Config.params['someKey']}" /> instead of : <mx:Text id="errorText" text="{Config.params[0]}" /> where Config.params is ArrayList (obviously i couldn't use ArrayList since it doesn't allow selecting a value by key) So the question is how to bind the key/value pairs loaded form XML. I don't want to go manually set variables, i want to bind them so when they are loaded the are set automatically. Did anyone had to do something like that ?

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  • BASH: How to count all the human readable files?

    - by user1687406
    I'm taking an intro course to UNIX and have a homework question that follows: How many files in the previous question are text files? A text file is any file containing human-readable content. (TRICK QUESTION. Run the file command on a file to see whether the file is a text file or a binary data file! If you simply count the number of files with the ".txt" extension you will get no points for this question.) The previous question simply asked how many regular files there were, which was easy to figure out by doing find . -type f | wc -l I'm just having trouble determining what "human readable content" is, since I'm assuming it means anything besides binary/assembly, but I thought that's what -type f displays. Maybe that's what the professor meant by saying "trick question"? This question has a follow up later that also asks "What text files contain the string "csc" in any mix of upper and lower case?". Obviously "text" is referring to more than just .txt files, but I need to figure out the first question to determine this!

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  • The new operator in C# isn't overriding base class member

    - by Dominic Zukiewicz
    I am confused as to why the new operator isn't working as I expected it to. Note: All classes below are defined in the same namespace, and in the same file. This class allows you to prefix any content written to the console with some provided text. public class ConsoleWriter { private string prefix; public ConsoleWriter(string prefix) { this.prefix = prefix; } public void Write(string text) { Console.WriteLine(String.Concat(prefix,text)); } } Here is a base class: public class BaseClass { protected static ConsoleWriter consoleWriter = new ConsoleWriter(""); public static void Write(string text) { consoleWriter.Write(text); } } Here is an implemented class: public class NewClass : BaseClass { protected new static ConsoleWriter consoleWriter = new ConsoleWriter("> "); } Now here's the code to execute this: class Program { static void Main(string[] args) { BaseClass.Write("Hello World!"); NewClass.Write("Hello World!"); Console.Read(); } } So I would expect the output to be Hello World! > Hello World! But the output is Hello World Hello World I do not understand why this is happening. Here is my thought process as to what is happening: The CLR calls the BaseClass.Write() method The CLR initialises the BaseClass.consoleWriter member. The method is called and executed with the BaseClass.consoleWriter variable Then The CLR calls the NewClass.Write() The CLR initialises the NewClass.consoleWriter object. The CLR sees that the implementation lies in BaseClass, but the method is inherited through The CLR executes the method locally (in NewClass) using the NewClass.consoleWriter variable I thought this is how the inheritance structure works? Please can someone help me understand why this is not working?

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  • ASP.NET - Call required field validator before AJAX modalpopup, client side

    - by odinel
    I have an ASP.NET/C# application. The user fills out a form with required fields, then clicks a submit button. An AJAX popup message is then displayed, and if they confirm, their information is posted back to the server. The problem is that the AJAX popup is fired BEFORE the req validator. I need to interrupt this and run the req validator, and then if successful show the popup. I know the req validator is working, because if you cancel the popup message, the req text is shown next to the fields. Textbox and AJAX control code is here: <table> <tr> <td>Name</td> <td> <asp:TextBox ID="txtName" runat="server" CssClass="textBox" AutoPostBack="true"></asp:TextBox> <asp:RequiredFieldValidator ID="reqName" runat="server" Text="*" ControlToValidate="txtName" ValidationGroup="trade" ForeColor="White"></asp:RequiredFieldValidator> </td> </tr> <tr> <td>Address</td> <td> <asp:TextBox ID="txtAdd1" runat="server" CssClass="textBox"></asp:TextBox> <asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" Text="*" ControlToValidate="txtAdd1" ValidationGroup="trade" ForeColor="White"></asp:RequiredFieldValidator> </td> </tr> <tr> <td></td> <td> <asp:Button ID="btnSubmitEnquiry" runat="server" CssClass="buttonText" Text="Submit Enquiry" ValidationGroup="trade" /> </td> </tr> </table> <ajax:ModalPopupExtender ID="ModalPopupExtender1" runat="server" okcontrolid="lnkCancel" targetcontrolid="btnSubmitEnquiry" popupcontrolid="pnlConfirm" popupdraghandlecontrolid="PopupHeader" drag="true" ></ajax:ModalPopupExtender> <asp:Button Text="targetbutton" ID="btnConfTgt" runat="server" Style="display: none" /> <asp:Panel ID="pnlConfirm" style="display:none" runat="server"> <div class="PopupContainer"> <div class="PopupBody"> <br /> <div align="center"> <asp:label ID="Label1" runat="server" CssClass="lblConfirmpopup"> Message goes here </asp:label> </div> <br /><br /><br /> <div align="center"> <asp:LinkButton ID="lnkCancel" runat="server" visible="true" Text="Cancel" CommandName="Update" BorderColor="#FFFFFF" BackColor="#000000" BorderWidth="3" BorderStyle="Double" ForeColor="White" Font-Size="13pt" Font-Underline="False"></asp:LinkButton> <asp:LinkButton ID="lnkConfirm" runat="server" visible="true" Text="Submit Enquiry" CommandName="Update" BorderColor="#FFFFFF" BackColor="#000000" BorderWidth="3" BorderStyle="Double" ForeColor="White" Font-Size="13pt" Font-Underline="False" OnClick="btnSubmitEnquiry_Click"></asp:LinkButton> </div> </div> </div> </asp:Panel> I've tried coding the first submit button to call the client-side req validator method, but no joy; it still shows the popup before the req validator. If there's no simple solution, I was thinking of perhaps an 'outside the box' solution, maybe hiding the initial Submit button after the req validation has passed, then showing an additional button with the popup control attached to it. Not sure how I'd be able to achieve this though. Thanks

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  • How can I see what capybara found in a failing cucumber step?

    - by ajmurmann
    I started migrating from cucumber + webrat to cucumber + capybara. Now the behavior of "I should see " seems to be somewhat different. Most of these fail now, although I didn't change anything on the page. I replaced the snippet that should be found with some stuff that is on every page and for some text it works and for other text it doesn't. I can't find any pattern in what is found in the page's content and what is not. Webrat used to print what the page content is that it found, in case it did not contain the required phrase. Is there anyway to have capybara show what text it got from the page in which it tried to find the text?

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  • Get Process ID of Program Started with C# Process.Start

    - by ThaKidd
    Thanks in advance of all of your help! I am currently developing a program in C# 2010 that launches PLink (Putty) to create a SSH Tunnel. I am trying to make the program able to keep track of each tunnel that is open so a user may terminate those instances that are no longer needed. I am currently using System.Diagnostics.Process.Start to run PLink (currently Putty being used). I need to determine the PID of each plink program when it is launched so a user can terminate it at will. Question is how to do that and am I using the right .Net name space or is there something better? Code snippet: private void btnSSHTest_Click(object sender, EventArgs e) { String puttyConString; puttyConString = "-ssh -P " + cboSSHVersion.SelectedText + " -" + txtSSHPort.Text + " -pw " + txtSSHPassword.Text + " " + txtSSHUsername.Text + "@" + txtSSHHostname.Text; Process.Start("C:\\Program Files (x86)\\Putty\\putty.exe", puttyConString); }

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  • How to close a JFrame in the middle of a program

    - by Nick Gibson
    public class JFrameWithPanel extends JFrame implements ActionListener, ItemListener { int packageIndex; double price; double[] prices = {49.99, 39.99, 34.99, 99.99}; DecimalFormat money = new DecimalFormat("$0.00"); JLabel priceLabel = new JLabel("Total Price: "+price); JButton button = new JButton("Check Price"); JComboBox packageChoice = new JComboBox(); JPanel pane = new JPanel(); TextField text = new TextField(5); JButton accept = new JButton("Accept"); JButton decline = new JButton("Decline"); JCheckBox serviceTerms = new JCheckBox("I Agree to the Terms of Service.", false); JTextArea termsOfService = new JTextArea("This is a text area", 5, 10); public JFrameWithPanel() { super("JFrame with Panel"); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); pane.add(packageChoice); setContentPane(pane); setSize(250,250); setVisible(true); packageChoice.addItem("A+ Certification"); packageChoice.addItem("Network+ Certification "); packageChoice.addItem("Security+ Certifictation"); packageChoice.addItem("CIT Full Test Package"); pane.add(button); button.addActionListener(this); pane.add(text); text.setEditable(false); text.setBackground(Color.WHITE); text.addActionListener(this); pane.add(termsOfService); termsOfService.setEditable(false); termsOfService.setBackground(Color.lightGray); pane.add(serviceTerms); serviceTerms.addItemListener(this); pane.add(accept); accept.addActionListener(this); pane.add(decline); decline.addActionListener(this); } public void actionPerformed(ActionEvent e) { packageIndex = packageChoice.getSelectedIndex(); price = prices[packageIndex]; text.setText("$"+price); Object source = e.getSource(); if(source == accept) { if(serviceTerms.isSelected() == false) { JOptionPane.showMessageDialog(null,"Please accept the terms of service.", "Terms of Service", JOptionPane.ERROR_MESSAGE); } else { JOptionPane.showMessageDialog(null,"Thank you. We will now move on to registering your product."); pane.dispose(); } } else if(source == decline) { System.exit(0); } } public void itemStateChanged(ItemEvent e) { int select = e.getStateChange(); } public static void main(String[] args) { String value1; int constant = 1, invalidNum = 0, answerParse, packNum, packPrice; JOptionPane.showMessageDialog(null,"Hello!"+"\nWelcome to the CIT Test Program."); JOptionPane.showMessageDialog(null,"IT WORKS!"); } }//class How do I get this frame to close so that my JOptionPane Message Dialogs can continue in the program without me exiting the program completely. EDIT: I tried .dispose() but I get this: cannot find symbol symbol : method dispose() location: class javax.swing.JPanel pane.dispose(); ^

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  • radgridview delete update in asp.net

    - by abhi
    i have written the follwing to display data from the datagrid and den insert new rows but how do i perform update and delete plss help here's my code using System; using System.Data; using System.Configuration; using System.Collections; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; using Telerik.Web.UI; using System.Data.SqlClient; public partial class Default6 : System.Web.UI.Page { string strQry, strCon; SqlDataAdapter da; SqlConnection con; DataSet ds; protected void Page_Load(object sender, EventArgs e) { strCon = "Data Source=MINETDEVDATA; Initial Catalog=ML_SuppliersProd; User Id=sa; Password=@MinetApps7;"; con = new SqlConnection(strCon); strQry = "SELECT * FROM table1"; da = new SqlDataAdapter(strQry, con); SqlCommandBuilder cmdbuild = new SqlCommandBuilder(da); ds = new DataSet(); da.Fill(ds, "table1"); RadGrid1.DataSource = ds.Tables["table1"]; RadGrid1.DataBind(); Label3.Visible = false; Label4.Visible = false; Label5.Visible = false; txtFname.Visible = false; txtLname.Visible = false; txtDesignation.Visible = false; } protected void Submit_Click(object sender, EventArgs e) { Label3.Visible = true; Label4.Visible = true; Label5.Visible = true; txtFname.Visible = true; txtLname.Visible = true; txtDesignation.Visible = true; } protected void Button2_Click(object sender, EventArgs e) { DataSet ds = new DataSet("EmployeeSet"); da.Fill(ds, "table1"); DataTable EmployeeTable = ds.Tables["table1"]; DataRow row = EmployeeTable.NewRow(); row["Fname"] = txtFname.Text.ToString(); row["Lname"] = txtLname.Text.ToString(); row["Designation"] = txtDesignation.Text.ToString(); EmployeeTable.Rows.Add(row); da.Update(ds, "table1"); //RadGrid1.DataSource = ds.Tables["table1"]; //RadGrid1.DataBind(); txtFname.Text = ""; txtLname.Text = ""; txtDesignation.Text = ""; } protected void RadGrid1_DeleteCommand(object source, GridCommandEventArgs e) { } } }

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  • How can I create an editable combo box in HTML/Javascript?

    - by Christian Davén
    I need to let users select an item from a dropdown list, but also allow them to instead enter any text, even if it doesn't match an item in the list. How can I achieve this on a web page with HTML and Javascript? The select field doesn't let users enter text, and the input text field doesn't show the preferred alternatives. All items must show if the user opens the dropdown, so it can't be a simple auto-complete that only shows matching items.

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  • How can I make a Yes/No combobox return true/false?

    - by Kasper Hansen
    I am new to creating forms in Visual Studio and C#. But I made a UI that has some comboboxes where the DropDownStyle is DropDownList. The items shown is Yes and No. But I need to assign this as a boolean value to a property on some object ai and currently do this: if (cmbExample.Text == "Yes") { ai.isPacketType = true; } else if (cmbExample.Text == "No") { ai.isPacketType = false; } I basically want to do something like this (or some other one liner): ai.isPacketType = cmbExample.Text; How do I link the Text Yes to the value true and No to false?

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  • jQuery sortable drop within itself.

    - by Janis Peisenieks
    So my question here is: Can I place a sortable element within another sortable element of the same level. Example: <ul class="sortable"> <li class="subsortable">Some text</li> <li class="subsortable">Some text</li> </ul> into: <ul class="sortable"> <li class="subsortable">Some text<li class="subsortable">Some text</li></li> </ul> I've been trying to do this for a day now, and I can't seem to find a way to do this.

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  • Can I connect to SQL from JavaScript MVC?

    - by user54197
    I am populating a list of names that will be added to my Sql Database. In this simple case, how do I send the information to SQL server without my page being refreshed? <script type="text/javascript"> function addNewRow() { $('#displayPropertyTable tr:last').after('<tr><td style="font-size:smaller;" class="name"></td><td style="font-size:smaller;" class="address"></td></tr>'); var $tr = $('#displayPropertyTable tr:last'); var propertyCondition = $('#txtPropAddress').val(); if (propertyCondition != "") { $tr.find('.name').text($('#txtPropName').val()); $tr.find('.address').text($('#txtPropAddress').val()); } } </script> ... <table id="displayPropertyTable" width= "100%"> <tr> <td style="font-size:smaller;" class="name"></td> <td style="font-size:smaller;" class="address"></td> </tr> </table> ... <table> <tr> <td><b>Name</b></td> <td colspan="2"><input id="txtPropName" type="text" /></td> </tr> <tr> <td><b>Address</b></td> <td colspan="2"><input id="txtPropAddress" type="text" /></td> </tr> </table> ... <button onclick="addNewRow();">Add</button>

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  • How do I display alternate languages in Interface Builder? (Xcode5)

    - by Anthony F
    The iOS project is using Base Localization with localizable strings set up for the Storyboard in English and German. Everything is working properly when I change the language for the simulator, but some of the text is getting truncated in German. I would like to view the German text in Interface builder so that it's easier to fix the constraints on the text labels and fields. It seems like this should just be a view setting or something, but I can't seem to find anything obvious.

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  • fill UIWebVIew TextInput with custom keyboard

    - by user319097
    For an app I am working on I want a custom keyboard to come up when you tap on an input field in a UIWebview, for example for UITextView i use this code : myText.text = [myText.text stringByAppendingString:@"a"]; but i don't know how can i fill a text field in UIWebVIew Any help would be very much appreciated; thanks!

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  • How do I handle the Maybe result of at in Control.Lens.Indexed without a Monoid instance

    - by Matthias Hörmann
    I recently discovered the lens package on Hackage and have been trying to make use of it now in a small test project that might turn into a MUD/MUSH server one very distant day if I keep working on it. Here is a minimized version of my code illustrating the problem I am facing right now with the at lenses used to access Key/Value containers (Data.Map.Strict in my case) {-# LANGUAGE OverloadedStrings, GeneralizedNewtypeDeriving, TemplateHaskell #-} module World where import Control.Applicative ((<$>),(<*>), pure) import Control.Lens import Data.Map.Strict (Map) import qualified Data.Map.Strict as DM import Data.Maybe import Data.UUID import Data.Text (Text) import qualified Data.Text as T import System.Random (Random, randomIO) newtype RoomId = RoomId UUID deriving (Eq, Ord, Show, Read, Random) newtype PlayerId = PlayerId UUID deriving (Eq, Ord, Show, Read, Random) data Room = Room { _roomId :: RoomId , _roomName :: Text , _roomDescription :: Text , _roomPlayers :: [PlayerId] } deriving (Eq, Ord, Show, Read) makeLenses ''Room data Player = Player { _playerId :: PlayerId , _playerDisplayName :: Text , _playerLocation :: RoomId } deriving (Eq, Ord, Show, Read) makeLenses ''Player data World = World { _worldRooms :: Map RoomId Room , _worldPlayers :: Map PlayerId Player } deriving (Eq, Ord, Show, Read) makeLenses ''World mkWorld :: IO World mkWorld = do r1 <- Room <$> randomIO <*> (pure "The Singularity") <*> (pure "You are standing in the only place in the whole world") <*> (pure []) p1 <- Player <$> randomIO <*> (pure "testplayer1") <*> (pure $ r1^.roomId) let rooms = at (r1^.roomId) ?~ (set roomPlayers [p1^.playerId] r1) $ DM.empty players = at (p1^.playerId) ?~ p1 $ DM.empty in do return $ World rooms players viewPlayerLocation :: World -> PlayerId -> RoomId viewPlayerLocation world playerId= view (worldPlayers.at playerId.traverse.playerLocation) world Since rooms, players and similar objects are referenced all over the code I store them in my World state type as maps of Ids (newtyped UUIDs) to their data objects. To retrieve those with lenses I need to handle the Maybe returned by the at lens (in case the key is not in the map this is Nothing) somehow. In my last line I tried to do this via traverse which does typecheck as long as the final result is an instance of Monoid but this is not generally the case. Right here it is not because playerLocation returns a RoomId which has no Monoid instance. No instance for (Data.Monoid.Monoid RoomId) arising from a use of `traverse' Possible fix: add an instance declaration for (Data.Monoid.Monoid RoomId) In the first argument of `(.)', namely `traverse' In the second argument of `(.)', namely `traverse . playerLocation' In the second argument of `(.)', namely `at playerId . traverse . playerLocation' Since the Monoid is required by traverse only because traverse generalizes to containers of sizes greater than one I was now wondering if there is a better way to handle this that does not require semantically nonsensical Monoid instances on all types possibly contained in one my objects I want to store in the map. Or maybe I misunderstood the issue here completely and I need to use a completely different bit of the rather large lens package?

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