[...]

 GL>        hwnd_menu = WinWindowFromID(handle,IDM_TIMER);              
 GL>   rc = WinEnableMenuItem(hwnd_menu,IDM_START,TRUE);                
 GL> break;

you are querying the wrong id. IDM_TIMER is a menu-item-id, not the menu-id.

try this:

hWndMenu = WinWindowFromID(hWndFrame, FID_MENU);
or: hWndMenu = WinWindowFromID(WinQueryWindow(hWnd, QW_PARENT), FID_MENU);

rc = WinEnableMenuItem(hWndMenu, IDM_START, FALSE);


  ..jd