Question: In order to take a screenshot of a specific window, I need to place a white colored TForm behind that window. What Windows API could I use to change the z-order of my window and place it correctly ?

Answer: 
Try the [`SetWindowPos()`](http://msdn.microsoft.com/en-us/library/ms633545%28VS.85%29.aspx) function.
If you can get the handle of the window you want in front then I would assume that:
Pseudo Code:

```
MyAppWindow.BringToFront

```

followed by

```
TargetWindow.BringToFront

```

Should have the desired effect, yes?