ALT as a click modifier

[Riccardo Mottola]

Hi,

after William's advice, I changed Graphos mouse-event key-modifier for 
certain operations to Alternate, to be more similar to other applications.

Graphos handles three different modifiers: shift, control, alt (method 
below).

Originally "alt" was mapped to NSCommandKeyMask. This would usually work 
fine on GNUstep with the standard setup, but on Mac you needed 
"command", as it is obvious. Now I set it to Alternate and it works like 
a charm on Mac, but not on GNUstep: there is no key combination that 
returns Alt.
I fear this is a similar problem as the one with alt as key-modifier for 
Emacs that Fred had.

I tried to remap keys using SystemPreferences, so that "command" becomes 
the WindowKey, thus I could map Alternate to Meta. That way, it works on 
GNUstep too, essentially it behaves like on Mac. However, The windows 
key is not always available, people usually run with the standard setup.

What options do I have?

1) #ifdef in the code for GNUstep and Mac. Horrible, but quick and works
2) Introduce preferences in graphos where the behaviour is customizable. 
This would be an advanced version of 1)
3) interpret both Command and Alternate as altClick. Looks dirty to me 
and probably would not work if on GS command gets mapped to control
4) change GS's gehaviour to issue "alt" if alt gets clicked and in case 
command is alt, both alt and command are returned as modifier (is this 
even possible?)
5) ...? what other option



Riccardo

---
    if([theEvent type] == NSLeftMouseDown
       || [theEvent type] == NSLeftMouseDragged)
    {
        if([theEvent modifierFlags] & NSShiftKeyMask)
            shiftclick = YES;
        else
            shiftclick = NO;
        if([theEvent modifierFlags] & NSAlternateKeyMask)
            altclick = YES;
        else
            altclick = NO;
        if([theEvent modifierFlags] & NSControlKeyMask)
            ctrlclick = YES;
        else
            ctrlclick = NO;
    }

    else if([theEvent type] == NSLeftMouseUp)
    {
        if(!([theEvent modifierFlags] & NSShiftKeyMask))
            shiftclick = NO;
        if(!([theEvent modifierFlags] & NSAlternateKeyMask))
            altclick = NO;
        if(!([theEvent modifierFlags] & NSControlKeyMask))
            ctrlclick = NO;
    }