Thats how my simple GUI system works^^(other naming convention, but the same way).
for example if i have a struct called TFrame (the T is from Type used in Delphi....)
'Methods' of it are called like TFrame_Free TFrame_Create TFrame_Paint
etc (First parameter is always the instance)
Greets Rackscha
MY Website with news of my projects: (for example my current Muliplayer Bomberman, GenesisPrecompiler for LiteC and TileMaster, an easy to use Tile editor) Sparetime-Development