Question

I am working on a virtual keyboard the problem is when i press a key on the virtual keyboard the window witch the data needs to be sent loses focus. How can i avoid that ?

Answer 1

When your keyboard form receives focus, part of the message it receives is the handle of the window that lost focus (wParam). Do what you need to do and set the focus back to the window that lost focus.

EDIT: See the documentation on WM_SETFOCUS

EDIT 2:

Also, you could use the following when creating your custom form:

procedure TMainForm.CreateParams(var Params: TCreateParams) ;
 //const WS_EX_NOACTIVATE = $8000000;
 begin
   inherited;
   Params.ExStyle := Params.ExStyle + WS_EX_NOACTIVATE;
 end;

To prevent your form from activating (taking focus from the other form). Like I alluded to in my comment, you should probably be using non-windowed controls for keys.