Handoko,
Thanks for new hint which crossed my reply.
I think there is something useful (for me) in this example, although I have to study Classes and Threads a bit to fully undertsand the code.
Currently I have defined animation buttons in question in the form as follows:
{ Put animation buttons on window }
CreateWindow('button', 'Animate', WS_CHILD Or WS_VISIBLE, 410, 0, 60, 20, hwindow, IDC_Anim_Go, 0, Nil);
CreateWindow('button', 'Stop', WS_CHILD Or WS_VISIBLE, 410, 50, 60, 20, hwindow, IDC_Anim_Stop, 0, Nil);
Probably they should rather be defined as another type of (click ?) button to detect them "globally" (like looking for a keyborad action).
LSE