The function to call is:
Function PostGuiEvent( id,source:TGadget=Null,data=0,mods=0,x=0,y=0,extra:Object=Null )
which can be found in maxgui.mod/event.bmx file
PostGuiEvent%(id%,source:TGadget="bbNullObject",data%=0,mods%=0,x%=0,y%=0,extra:Object="bbNullObject")="brl_maxgui_PostGuiEvent"
and looking in the .i file the call from c should be to "brl_maxgui_PostGuiEvent", I think... I don't see how you could call this directly from a dll though
Function PostGuiEvent( id,source:TGadget=Null,data=0,mods=0,x=0,y=0,extra:Object=Null )
which can be found in maxgui.mod/event.bmx file
PostGuiEvent%(id%,source:TGadget="bbNullObject",data%=0,mods%=0,x%=0,y%=0,extra:Object="bbNullObject")="brl_maxgui_PostGuiEvent"
and looking in the .i file the call from c should be to "brl_maxgui_PostGuiEvent", I think... I don't see how you could call this directly from a dll though