Thanks for your Answer but I still get the same Error Message (with your TRACKMOUSEEVENT structure) :/

The TrackMouseEvent function fails and returns zero. So I called (as msdn advised me) GetLastError() to get the error msg and it returns 998 which means: ERROR_NOACCESS Invalid access to memory location. Has anyone a clue what my OS is trying to tell me here? I guess the error is caused by the c++ struct which the function takes as parameter. ( TRACKMOUSEEVENT Struct on MSDN ) [DllImport("kernel32.dll", SetLastError=true)] static extern int GetLastError (); [DllImport("user32")] public static extern bool TrackMouseEvent(TRACKMOUSEEVENT lpEventTrack); [StructLayout( LayoutKind.Sequential,CharSet=CharSet.Ansi)] public struct TRACKMOUSEEVENT { public long cbSize; public long dwFlags; public long hwndTrack; public long dwHoverTime; } and in the C# App Constructor: TRACKMOUSEEVENT foo = new TRACKMOUSEEVENT(); foo.cbSize = Marshal.SizeOf(typeof(TRACKMOUSEEVENT)); foo.dwFlags = TME_NONCLIENT; foo.hwndTrack = (long)this.Handle; bool bar = TrackMouseEvent(foo); MessageBox.Show(""+GetLastError());

>The Show Desktop Icon (or Winkey+D) always minimizes my form and i couldn't find any way to prevent that. I discoverd that when I click "Show Desktop" that I get the Mesage WM_ACTIVATEAPP which tells me that my app gets deactivated and a thread from the explorer.exe Process gets activated. So far so good, but how do I prevent now that my app gets minimized?

I coded some kind of electronical Post-it notes and I want to stick them on the Windows Desktop, but how? The Show Desktop Icon (or Winkey+D) always minimizes my form and i couldn't find any way to prevent that. Another Idea would be to directly draw my stuff on the Desktop but I don't know how to register to the OnPaint event of the desktop to redraw my stuff. Thanks a lot in advance.

ok thanks.

I used http://www.codeproject.com/cs/media/perpxalpha\_sharp.asp to create a non-rectangular window. Then I tried to add a Label Form, but that didn't work (didn't show up). Therefore I thought that this maybe wouldn't be possible when you have a this type of window and tried directly to draw strings in my loaded bitmap: Graphics g = Graphics.FromImage(newBitmap); newBitmap.Dispose(); Font font = this.Font; Brush brush = new SolidBrush(Color.White); g.DrawString("Hallo wie geht es dir?",font,brush, 50,50); g.DrawImage(newBitmap,0,0); bitmap = newBitmap; newBitmap contains the loaded png (with alpha mask) image. The assignment of bitmap seems to crash (System.ArgumentException) because I disposed newBitmap. But why? I however assigned newBitmap again with g.DrawImage...

I used the WM_NCLBUTTONDBLCLK Event

Okay I found the answer for my first question.

How can i detect if a user has double-clicked the caption bar of a form (which normally causes the window to maximize)? And is there a way to add icons in the upper left corner (left from the quit, maximize and minimize boxes)?

After using Mutexes and also implementing FindFindow if hwnd is zero everything works fine, it's even way faster. Thanks a lot!

I'm sorry if my comments sound to offensive/overacting. I alway speak a little bit to rough, I'll try better next time :)

>You mentioned that your previous attempt didn't work. Were you using a mutex? No, I didn't say that. But indeed I aint using one cause I don't now I which Namespace the Mutex Class is (and yet I was to lazy to serch for that).

Weird. My Program doesn't get a message when the window is hidden.

What the hell... now it takes 1-2 seconds longer to start up. And btw. your code crashes. It seems to be that some proccess have a read protected process.MainModule Class. If I wrap around a try-catch it works. Thx for the answer

I want to avoid, that the user can start multiple instances of my programm. I found an article on CodeProject which helped, but it's a little bit confusing now when the user tries to start the programm and in doesn't start. Therefore I want, that the second instance activates (setting the windowstate to normal, calling Show() and Activate() the first instance (when it's minized or minimized to tray) before it closes itself. How do I do that?

Yes indeed, and everything is explained on MSDN. All my fault :( Actually I tried to convert a string into a point and also tried to sumarize two Points. Well, at least now I know how it works :)

What you need is a RichTextBox. Read about it on MSDN

The System.Drawing.Point Class has really a lot of missing Features. It has no TypeConverter and no support for operators like + and -. This is really weak. Is there any possibility to fix that issue? Sure... I could write an own Point class but that one won't be compatible with all the (drawing-)functions like DrawPoly and I don't want to write some ugly conversion code.

I guess It's like the same as including methods from the user32.dll: [DllImport("user32.dll", EntryPoint = "SendMessage", CharSet = CharSet.Auto, CallingConvention = CallingConvention.Winapi)] private static extern int SendMessage(IntPtr hWnd, int uMsg, int wParam, IntPtr lParam);

Next Question: Can I add something to the Point Class/Structure (I need to add the TypeConverter)?