2006-06Jun-02

KeyPress Event

Qualifier keys such as ALT, CTRL and SHIFT are prioritized in this order. When the user presses a combination of these three keys, the highest qualifier determines the key code. If, for instance, the ALT key is pressed with SHIFT, the key code is the same as if you pressed the key and just ALT. If the user instead presses SHIFT and CTRL, the key code switches to the CTRL combination. Only when the SHIFT key is pressed, you would end up with the SHIFT key code. The following table clarifies this for the U key:

              nKeyCode  nShiftAltCtrl
U                  117 	0
Shift+U             85 	1
Ctrl+U              21 	2
Alt+U               22 	4
Shift+Ctrl+U        21 	3
Shift+Alt+U         22 	5
Ctrl+Alt+U          22  6
Shift+Alt+Ctrl+U    22  7 (works only intermittently on my laptop)

The exception from the rule above is the SHIFT+ALT combination on keyboards that support an ALTGR key. SHIFT+ALT+Key and ALTGR+Key trigger the KeyPress event with nShiftAltCtrl=0 and the regular key code.

With ALT combinations, the key code corresponds to the physical location on a US keyboard. Pressing the key between T and U on a German keyboard results in a key code of 122, whereas it returns 121 with a US keyboard layout. However, with the ALT key, the key code is 21 in both cases.

This is the same side effect that occurs with ON KEY LABEL and with certain key combination to control child windows such as ALT+hypen (ALT+-) on a US keyboard which requires a German user to press ALT+ß.

Some special keys fire the KeyPress event, as well:

	nKeyCode	nShiftAltCtrl
Caps Lock+Shift+Alt	58	6 (not reliable)
	57	5 (not reliable)
Ctrl+Win+Alt	91	7
Shift+Alt+0	11	5

Some codes are identical. However, this doesn't necessarily apply to all qualifier key combinations.

	nKeyCode	nShiftAltCtrl
Ctrl++ / Ctrl+Pos1	29	2
Ctrl+H / Ctrl+Del	127	2
Ctrl+W / Ctrl+End	23	2
Ctrl+Left Arrow / Ctrl+Z	26	2
Ctrl+Right Arrow / Ctrl+B	2	2
Alt+0 / Alt+R	19	4
Shift+Alt+0	19	5
Ctrl+J / Ctrl+Enter	10	3
Shift+Ctrl+J	10	3
Shift+Z / Shift+F7	90	1
Shift+T / Shift+F1	84	1
Shift+U / Shift+F2	85	1
Shift+W / Shift+F4	87	1
Shift+Y / Shift+F6	89	1
Shift+X / Shift+F5	88	1
Shift+V / Shift+F3	86	1

The following combination do not work in conjunction with Ctrl or Ctrl+Shift. The first label is the corresponding key on a German keyboard, the second value on a US keyboard

German	US
^	'
1	1
2	2
3	3
4	4
5	5
6	6
7	7
8	8
9	9
ß	-
'	=
Ö	;
Ä	'
,	,
.	.
-	/

SHIFT+F10 is the context menu key and therefore returns nKeyCode=93 and nShiftAltCtrl=1.

With CapsLock, the key codes are inverted.