Add On_Paint and On_Erase_Background management to Common_Controls.

[NicoPy]

Try again...

[zertovitch]

A little detail: perhaps instead of:

raise Not_Set_Error with "Call_Default_Handler not Set";

raise Not_Set_Error
    with "Call_Default_Handler not set, should be Yes or No";

would be better to remind the context of that parameter.