Author: Jonas Bilinkevicius

I have an MDI application with many child forms. Their windowstate property is set 
to maximized. When a child form is created and shown, the form visibly resizes as 
it is shown. I would like the child form to open already maximized without the 
visible resizing. Any ideas?

Answer:

Preventing visible flicker when moving or sizing MDI children directly after their 
creation:

1   { ... }
2   public
3   { Public declarations }
4   
5   constructor Create(aOwner: TComponent); override;
6   end;
7   
8   implementation
9   
10  {$R *.DFM}
11  
12  constructor TMDIChild.Create(aOwner: TComponent);
13  var
14    crect: TRect;
15    chandle: HWND;
16  begin
17    { Get handle of MDI client window }
18    chandle := application.mainform.clienthandle;
19    { Block redrawing of this window and its children }
20    Lockwindowupdate(chandle);
21    { Create this MDI child at default position, it will not be drawn yet
22  	due to the update block }
23    inherited Create(aOwner);
24    { Get the client windows rect and center this form in it }
25    Windows.GetClientrect(chandle, crect);
26    SetBounds((crect.right - width) div 2, (crect.bottom - height) div 2, width,
27      height);
28    { Release the block, this allows the form to redraw at the new position }
29    LockWindowUpdate(0);
30  end;