Hi,

There is no need to use WM_Update() and it has nothing to do with multibuffering. The window manager recognizes automatically if an area is invalid or not and handles the drawing.

To avoid flickering you can enable automatic use of multibuffering with a call of WM_MULTIBUF_Enable(). If you want to handle multibuffering manually call GUI_MULTIBUF_Begin() before and

Another possibility is to use the create flag WM_CF_MEMDEV on creating
a window/widget. If the flag is set, the window manager will use memory
devices automatically.

Best regards,
Sven