Description Peter Åstrand 2013-05-23 13:32:45 CEST

Moving from comment #8 of bug 3725. When pressing AltGr on the client, it should typically send ISO_Level3_Shift over VNC. In debug mode, this can be viewed as:

 Viewport:    Key pressed: 0xfe03 (0xfe03) '' => 0xfe03

During testing of bug 3725, I had a case where Alt_R was sent instead:

 Viewport:    Key pressed: 0xffea (0xffea) '' => 0xffea

xev however correctly gave ISO_Level3_Shift:

KeyPress event, serial 33, synthetic NO, window 0x4400001,
    root 0xb0, subw 0x0, time 5581540, (1171,618), root:(1177,672),
    state 0x2010, keycode 113 (keysym 0xfe03, ISO_Level3_Shift), same_screen YES,
    XKeysymToKeycode returns keycode: 124
    XLookupString gives 0 bytes: 
    XmbLookupString gives 0 bytes: 
    XFilterEvent returns: False

KeyRelease event, serial 33, synthetic NO, window 0x4400001,
    root 0xb0, subw 0x0, time 5581596, (1171,618), root:(1177,672),
    state 0x2090, keycode 113 (keysym 0xfe03, ISO_Level3_Shift), same_screen YES,
    XKeysymToKeycode returns keycode: 124
    XLookupString gives 0 bytes: 
    XFilterEvent returns: False

The factor that caused this problem was that two XKB layouts were defined: USA and Sweden. The last one was active. One can see this due to the strange state of 0x2090. Also note the output from xmodmap -pke:

keycode 113 = Alt_R Meta_R ISO_Level3_Shift

Also, here's how the xmodmap looked like:

shift       Shift_L (0x32),  Shift_R (0x3e)
lock        Caps_Lock (0x42)
control     Control_L (0x25),  Control_R (0x6d)
mod1        Alt_L (0x40),  Alt_R (0x71),  Meta_L (0x9c)
mod2        Num_Lock (0x4d)
mod3        Down (0x68)
mod4        Super_L (0x73),  Super_R (0x74),  Super_L (0x7f),  Hyper_L (0x80)
mod5        Mode_switch (0x8),  ISO_Level3_Shift (0x7c)


It is possible to work around this problem either by only using one client side layout at a time, or making sure that the active layout is the first one. However, we should see that vncviewer does wrong in this case; it should really produce ISO_Level3_Shift, just as xev does.