Author: Jonas Bilinkevicius

I have created a form which is snapped to the top of the screen. When I change the 
size of the Windows Desktop, the visible form isn't resized accordingly.

Answer:

I use the following code and it works quite good, even if the desktop size is 
changed:

1   type
2     TForm1 = class(TForm)
3     private
4       procedure WMWindowPosChanging(var message: TWMWindowPosMsg);
5         message WM_WINDOWPOSCHANGING;
6   
7       { ... }
8   
9   implementation
10  
11  { ... }
12  
13  var
14    WorkAreaRect: TRect;
15    NewWorkAreaFlag: Boolean;
16  
17    { ... }
18  
19  procedure TForm1.WMWindowPosChanging(var message: TWMWindowPosMsg);
20  begin
21    if (WindowState <> wsMaximized) then
22    begin
23      if (message.WindowPos.Flags and SWP_NOMOVE) = 0 then
24      begin {form is moved}
25        if NewWorkAreaFlag then
26        begin {workarea might have changed since last call}
27          SystemParametersInfo(SPI_GETWORKAREA, 0, @WorkAreaRect, 0);
28        end;
29        {snap form to border here, something 
30  			like Message.WindowPos.X := WorkAreaRect.Left if near to left border}
31        { ... }
32      end;
33      NewWorkAreaFlag := ((message.WindowPos.Flags and (SWP_NOMOVE or SWP_NOSIZE)) <>
34        0);
35      {True if form was (probably) dropped => get workarea again}
36    end;
37  end;
38  
39  { ... }
40  
41  initialization
42    NewWorkAreaFlag := True;