In this section:
This format code, %sm (Modify System Menu), is used to augment the system menu and is constructed in a manner similar to %mn (Menu). A grave accent modifier (`) is used in order to replace the menu rather than to add to it.
For example:
i=winio@('%sm[Alpha,~Beta]',Alpha_func,Beta_cntrl,Beta_func)
will add the menu items Alpha and Beta to the end of the system menu. Beta will be greyed when the control variable Beta_cntrl has a zero value. Alpha_func and Beta_func are the associated call-back functions. If a grave accent is supplied in the form %`sm, then the two menu items will replace the system menu.
The tab character CHAR(9) (or CHAR(20)) attaches an accelerator key to a particular menu item and its associated call-back function. The syntax is the same as that for %mn above.