Value
| Description
|
0 15
| Specifies the repeat count. The value is the number of times the keystroke is
repeated as a result of the user holding down the key.
|
1623
| Specifies the scan code. The value depends on the original equipment
manufacturer (OEM).
|
24
| Specifies whether the key is an extended key, such as the right-hand ALT and CTRL keys that appear on an enhanced 101- or 102-key keyboard. The value is 1 if
it is an extended key; otherwise, it is 0.
|
2528
| Reserved; do not use.
|
29
| Specifies the context code. The value is 1 if the ALT key is held down while the key is pressed; otherwise, the value is 0.
|
30
| Specifies the previous key state. The value is 1 if the key is down before the
message is sent, or it is 0 if the key is up.
|
31
| Specifies the transition state. The value is 1 if the key is being released,
or it is 0 if the key is being pressed.
|
The WM_SYSDEADCHAR message is sent to the window with the keyboard focus when
a WM_SYSKEYDOWN message is translated by the TranslateMessage function. WM_SYSDEADCHAR specifies the character code of a system dead key 
that is, a dead key that is pressed while holding down the ALT key.
WM_SYSDEADCHAR
chCharCode = (TCHAR) wParam; // character code
lKeyData = lParam; // key data
Parameters
chCharCode
Value of wParam. Specifies the character code generated by the system dead key