I frequently need to enter key combinations that require pressing and holding
both the Shift and Alt (Meta) keys.  An example would be the Emacs mark-word
command (bound to M-@ by default): to enter it, I would press and hold Shift,
press and hold Alt, and then press the @/2 key on the keyboard.

In xorg-x11-drv-keyboard-1.0.1.3-1.2 (the Fedore Core 5 package), the state
modifiers depend on the order in which the keys are pressed.

Specifically, if I press Alt-Shift-@, the state modifier returned on the
keypress event is 0x9 (0x1 = Shift, 0x8 = Alt) according to xev:

KeyPress event, serial 28, synthetic NO, window 0x3e00001,
    root 0x4c, subw 0x0, time 3094865719, (86,91), root:(90,110),
    state 0x9, keycode 11 (keysym 0x40, at), same_screen YES,
    XLookupString gives 1 bytes: (40) "@"
    XmbLookupString gives 1 bytes: (40) "@"
    XFilterEvent returns: False

This is correct.

However, if I press Shift-Alt-@ (that is, I press the Shift key before the Alt
key), according to xev, the state modifier returned on the keypress event is 0x1:

KeyPress event, serial 28, synthetic NO, window 0x3e00001,
    root 0x4c, subw 0x0, time 3094891814, (90,70), root:(94,89),
    state 0x1, keycode 11 (keysym 0x40, at), same_screen YES,
    XLookupString gives 1 bytes: (40) "@"
    XmbLookupString gives 1 bytes: (40) "@"
    XFilterEvent returns: False

This is *not* correct; the Alt state modifier has been lost.

This is a very big deal to me, because the way I tend to type, I almost always
hit the Shift key before the Alt key.

Furthermore, this doesn't happen 100% of the time.  Occasionally the X server
will work correctly; that is, the modifier keys don't depend on the order in
which they are pressed.  However, I've been unable to figure out what (if
anything) I did to get it to work correctly.