Avoid ReRunning PopupMenu Actions When Choice Does Not Change

In those cases where you are using PopMenus on control panels, you may wish to avoid having the popmenu procedure execute after a mouse up in the case where the selected choice has not changed. This code snippet compares the menu choice with the string stored in the userData to cause such a behavior.

// check whether a popup has been changed
// uses userdata
// returns 1 when changed or 0 when not
Static Function X_PopHasChanged(STRUCT WMPopupAction &pa)   
    variable vv = abs(cmpstr(pa.popStr,pa.userdata))
    if (vv != 0)
        pa.userdata = pa.popstr
    endif
    return vv
end

Here is an example use.

Static Function Do_PopupMenuAction(STRUCT WMPopupAction &pa) : PopupMenuControl 
    switch( pa.eventCode )
        case 2:   // mouse up
            if (!ModuleName#X_PopHasChanged(pa))
                return 0
            endif
            switch(pa.popNum)
                case 1:         // ...

Note also the use of STATIC for the function call and ModuleName# for the preface to the X_PopHasChanged(...) function call. Use these options as needed especially to avoid clashes with other packages that may use the same (static) function name in their own Module (or Independent Module).

UPDATE: The newest version will not give a warning when checking with ipt lint.