For XP up, use WS_EX_COMPOSITED bitmask…
WS_EX_COMPOSITED: Paints all descendants of a window in
bottom-to-top painting order using DOUBLE-BUFFERING.
This cannot be used if the window has a class style of
either CS_OWNDC or CS_CLASSDC.
1. Define your constant:
CONST WS_EX_COMPOSITED = 0x02000000L
2. Use it in the extended sytle portion of your window creation routine:
MyForm = (Name$, x, y, w, h, WS_THIS|WS_THAT, WS_EX_COMPOSITED)