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  4. Make a control a child of the Desktop?

Make a control a child of the Desktop?

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  • R Rocky Moore

    Nish [BusterBoy] wrote: The desktop's HWND is 0 As you have noticed from other posts, the GetDesktopWindow() does not actually return (0). If you look at your window tree with Spy, it returns the window at the very top of the tree. At least it does under the normal API in C++, but in C# it only wants to return (0) which is useless. In C# I call it as:

    [DllImport("user32.dll")]
    extern static IntPtr GetDesktopWindow();

    and later in the class I simply use:

    GetDesktopWindow();

    It always seems to get zero, am I doing something wrong here? Rocky Moore

    R Offline
    R Offline
    Rama Krishna Vavilala
    wrote on last edited by
    #10

    I get correct values all the time.:wtf:

    R 1 Reply Last reply
    0
    • R Rocky Moore

      Rama Krishna wrote: I get correct values all the time. ::Throwing Tantrum:: ::Feet Stumping:: ::Purple Face:: That's not fair, I just get zeros! ;) So, they code you use and actual get a value is the same as I showed in the last post? Rocky Moore

      R Offline
      R Offline
      Rama Krishna Vavilala
      wrote on last edited by
      #11

      Here is the code as it is:-

      using System;
      using System.Drawing;
      using System.Collections;
      using System.ComponentModel;
      using System.Windows.Forms;
      using System.Data;

      namespace WindowsApplication2
      {
      /// /// Summary description for Form1.
      ///
      public class Form1 : System.Windows.Forms.Form
      {
      /// /// Required designer variable.
      ///
      private System.ComponentModel.Container components = null;

      	\[System.Runtime.InteropServices.DllImport("User32.dll")\]
      	extern static IntPtr GetDesktopWindow();
      
      	public Form1()
      	{
      		//
      		// Required for Windows Form Designer support
      		//
      		InitializeComponent();
      
      		IntPtr hwnd = GetDesktopWindow();
      
      		System.Diagnostics.Debug.Assert(hwnd != IntPtr.Zero);
      	}
      
      	/// /// Clean up any resources being used.
      	/// 
      	protected override void Dispose( bool disposing )
      	{
      		if( disposing )
      		{
      			if (components != null) 
      			{
      				components.Dispose();
      			}
      		}
      		base.Dispose( disposing );
      	}
      
      	#region Windows Form Designer generated code
      	/// /// Required method for Designer support - do not modify
      	/// the contents of this method with the code editor.
      	/// 
      	private void InitializeComponent()
      	{
      		this.components = new System.ComponentModel.Container();
      		this.Size = new System.Drawing.Size(300,300);
      		this.Text = "Form1";
      	}
      	#endregion
      
      	/// /// The main entry point for the application.
      	/// 
      	\[STAThread\]
      	static void Main() 
      	{
      		Application.Run(new Form1());
      	}
      }
      

      }

      R 1 Reply Last reply
      0
      • R Rama Krishna Vavilala

        I get correct values all the time.:wtf:

        R Offline
        R Offline
        Rocky Moore
        wrote on last edited by
        #12

        Rama Krishna wrote: I get correct values all the time. ::Throwing Tantrum:: ::Feet Stumping:: ::Purple Face:: That's not fair, I just get zeros! ;) So, they code you use and actual get a value is the same as I showed in the last post? Rocky Moore

        R 1 Reply Last reply
        0
        • R Rama Krishna Vavilala

          Here is the code as it is:-

          using System;
          using System.Drawing;
          using System.Collections;
          using System.ComponentModel;
          using System.Windows.Forms;
          using System.Data;

          namespace WindowsApplication2
          {
          /// /// Summary description for Form1.
          ///
          public class Form1 : System.Windows.Forms.Form
          {
          /// /// Required designer variable.
          ///
          private System.ComponentModel.Container components = null;

          	\[System.Runtime.InteropServices.DllImport("User32.dll")\]
          	extern static IntPtr GetDesktopWindow();
          
          	public Form1()
          	{
          		//
          		// Required for Windows Form Designer support
          		//
          		InitializeComponent();
          
          		IntPtr hwnd = GetDesktopWindow();
          
          		System.Diagnostics.Debug.Assert(hwnd != IntPtr.Zero);
          	}
          
          	/// /// Clean up any resources being used.
          	/// 
          	protected override void Dispose( bool disposing )
          	{
          		if( disposing )
          		{
          			if (components != null) 
          			{
          				components.Dispose();
          			}
          		}
          		base.Dispose( disposing );
          	}
          
          	#region Windows Form Designer generated code
          	/// /// Required method for Designer support - do not modify
          	/// the contents of this method with the code editor.
          	/// 
          	private void InitializeComponent()
          	{
          		this.components = new System.ComponentModel.Container();
          		this.Size = new System.Drawing.Size(300,300);
          		this.Text = "Form1";
          	}
          	#endregion
          
          	/// /// The main entry point for the application.
          	/// 
          	\[STAThread\]
          	static void Main() 
          	{
          		Application.Run(new Form1());
          	}
          }
          

          }

          R Offline
          R Offline
          Rocky Moore
          wrote on last edited by
          #13

          That worked, must be something in the code around it that is causing the problem. At least now I can look in the right direction. Thanks for the test! I should have thought to test it in a different project first :-O Rocky Moore

          N R 2 Replies Last reply
          0
          • R Rocky Moore

            That worked, must be something in the code around it that is causing the problem. At least now I can look in the right direction. Thanks for the test! I should have thought to test it in a different project first :-O Rocky Moore

            N Offline
            N Offline
            Neil Van Note
            wrote on last edited by
            #14

            Again, Try a IsWindow(hWnd) on the return value; it can't be assumed that it returns anything consistent, including null. The docs just do not specify null is or is not an invalid value.

            1 Reply Last reply
            0
            • R Rocky Moore

              That worked, must be something in the code around it that is causing the problem. At least now I can look in the right direction. Thanks for the test! I should have thought to test it in a different project first :-O Rocky Moore

              R Offline
              R Offline
              Rama Krishna Vavilala
              wrote on last edited by
              #15

              Are you calling any other unmanaged function before?

              1 Reply Last reply
              0
              • N Neil Van Note

                Nish, There is no reason to slam people for asking a question. Educate me, which functions that return window handles return something other than NULL to indicate a failure. Like I mentioned above, IsWindow is a much safer check, as the documentation for GetDesktopWindow doesn't indicate it could fail. I wonder what this returns for a process that is running in a state where there is no desktop? In addition, HWND_DESKTOP, which is defined as ((HWND)0), fails IsWindow(HWND_DESKTOP) under Windows XP Pro. I haven't checked Windows 2000 yet. Regards

                N Offline
                N Offline
                Nish Nishant
                wrote on last edited by
                #16

                Neil Van Note wrote: Nish, There is no reason to slam people for asking a question I wasn't slamming him :( I just thought it funny that MS was returning a 0 for GetDesktopWindow() and that too for a valid window handle, that of the desktop. Usually a 0 is supposed to indicate error or NULL as far as handles go. I apologize to all, if my words were insulting. I didnt meant them that way. Sorry! Nish


                Regards, Nish Native CPian. Born and brought up on CP. With the CP blood in him.

                1 Reply Last reply
                0
                • N Neil Van Note

                  GetDesktopWindow() does not necessarily return 0. It does not on my machine (Windows XP Pro), this morning it is returning 0x00010014. Regards

                  N Offline
                  N Offline
                  Nish Nishant
                  wrote on last edited by
                  #17

                  Could be that with XP pro, we actually can have multiple virtual desktops. Nish


                  Regards, Nish Native CPian. Born and brought up on CP. With the CP blood in him.

                  C 1 Reply Last reply
                  0
                  • R Rocky Moore

                    Nish [BusterBoy] wrote: The desktop's HWND is 0 As you have noticed from other posts, the GetDesktopWindow() does not actually return (0). If you look at your window tree with Spy, it returns the window at the very top of the tree. At least it does under the normal API in C++, but in C# it only wants to return (0) which is useless. In C# I call it as:

                    [DllImport("user32.dll")]
                    extern static IntPtr GetDesktopWindow();

                    and later in the class I simply use:

                    GetDesktopWindow();

                    It always seems to get zero, am I doing something wrong here? Rocky Moore

                    N Offline
                    N Offline
                    Nish Nishant
                    wrote on last edited by
                    #18

                    Rocky Moore wrote: As you have noticed from other posts, the GetDesktopWindow() does not actually return (0). Sorry Rocky, if I sounded insulting, but I have explained my reasons for smiling in my reply to Neil Van Note. It was the irony caused my MS that made me smile. Hope it's okay now :-) Nish


                    Regards, Nish Native CPian. Born and brought up on CP. With the CP blood in him.

                    R N 2 Replies Last reply
                    0
                    • N Nish Nishant

                      Rocky Moore wrote: As you have noticed from other posts, the GetDesktopWindow() does not actually return (0). Sorry Rocky, if I sounded insulting, but I have explained my reasons for smiling in my reply to Neil Van Note. It was the irony caused my MS that made me smile. Hope it's okay now :-) Nish


                      Regards, Nish Native CPian. Born and brought up on CP. With the CP blood in him.

                      R Offline
                      R Offline
                      Rocky Moore
                      wrote on last edited by
                      #19

                      Nish [BusterBoy] wrote: Sorry Rocky, if I sounded insulting, but I have explained my reasons for smiling in my reply to Neil Van Note. It was the irony caused my MS that made me smile. Hope it's okay now Wasn't taken that way, I am not a softy like others here :rolleyes: I truly appreciate any help I get, and Lord knows I need a lot at times ;) I still do not know why it was returning zero but I have done a bit of rewriting all around it and it seems to be working. One of those strange things, just glad I can finally move on. Now if I can just figure a way to get rid of the 'add a new row' row in the DataGrid that is using a dataset bound to the datasource instead of a dataview, my life would be much easier.. Thanks again! Rocky Moore

                      1 Reply Last reply
                      0
                      • N Nish Nishant

                        Could be that with XP pro, we actually can have multiple virtual desktops. Nish


                        Regards, Nish Native CPian. Born and brought up on CP. With the CP blood in him.

                        C Offline
                        C Offline
                        Corto Maltese
                        wrote on last edited by
                        #20

                        Multiple virtual desktops are more about extending window manager than being related to the OS (XP, Win2K, Win 9x, etc.). So, I guess we can have them with any MS OS flavor. It is just that with MS the actual line between the OS, shell and the window manager is kind of blurry (for the end user at least). -Gile

                        1 Reply Last reply
                        0
                        • N Nish Nishant

                          Rocky Moore wrote: As you have noticed from other posts, the GetDesktopWindow() does not actually return (0). Sorry Rocky, if I sounded insulting, but I have explained my reasons for smiling in my reply to Neil Van Note. It was the irony caused my MS that made me smile. Hope it's okay now :-) Nish


                          Regards, Nish Native CPian. Born and brought up on CP. With the CP blood in him.

                          N Offline
                          N Offline
                          Neil Van Note
                          wrote on last edited by
                          #21

                          Nish [BusterBoy] wrote: but I have explained my reasons for smiling in my reply to Neil Van Note The smiles where not the reason I thought you sounded insulting. It was the fact they are surrounding what you said, I quote... Nish [BusterBoy] wrote: Yeah, When he got the 0, he thought it was an error Either way, I am dropping it... Regards

                          N 1 Reply Last reply
                          0
                          • N Neil Van Note

                            Nish [BusterBoy] wrote: but I have explained my reasons for smiling in my reply to Neil Van Note The smiles where not the reason I thought you sounded insulting. It was the fact they are surrounding what you said, I quote... Nish [BusterBoy] wrote: Yeah, When he got the 0, he thought it was an error Either way, I am dropping it... Regards

                            N Offline
                            N Offline
                            Nish Nishant
                            wrote on last edited by
                            #22

                            Neil Van Note wrote: Either way, I am dropping it... Thanks Nish


                            Regards, Nish Native CPian. Born and brought up on CP. With the CP blood in him.

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