Can you make a Borderless Application Main Window in Windows, without WS_POPUP style?

Question

I want to create a window that will be the main window and that Windows itself recognizes as a main application window. However, when I make my window borderless, and witho

Answer 1

The following gets the job done:

hWnd = CreateWindow(...);
SetWindowLong(hWnd, GWL_STYLE, WS_POPUP | WS_MINIMIZEBOX);
SetWindowLong(hWnd, GWL_EXSTYLE, 0);
ShowWindow(hWnd, ...);

You were probably missing WS_MINIMIZEBOX.

Answer 2

A bit icky, but you can set the window region by putting this in YourForm.OnShow event:

var
  r: TRect;
begin
  r := ClientRect;
  OffsetRect(r, 0, GetSystemMetrics(SM_CYCAPTION));
  OffsetRect(r, GetSystemMetrics(SM_CXFRAME), GetSystemMetrics(SM_CYFRAME));
  SetWindowRgn(Handle, 
      CreateRectRgn(
          r.Left, r.Top, 
          ClientWidth + r.Left, ClientHeight + r.Top), True);

Answer 3

You need to override TForm.CreateParams and set or remove any style that you are interest in

procedure TYourForm.CreateParams(var Params: TCreateParams);
begin
  inherited CreateParams(Params);
  Params.Style := Params.Style and
  Params.ExStyle := Params.ExStyle or ;
end;