Use KF_ALTDOWN flag instead of GetKeyState(VK_MENU)

Use KF_ALTDOWN flag instead of GetKeyState(VK_MENU)

KF_ALTDOWN is more accurate than GetKeyState(VK_MENU). When usre presses
RightShift+RightAlt, the fake VK_CONTROL generated carries KF_ALTDOWN in
its flags but GetKeyState(VK_MENU) is clear.

BUG=30244
TEST=Verify RightAlt+RightShift does not change to RTL and issue 24888 does not regress. However, RightShift+RightAlt still changes RTL as this is the behavior of richedit.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=34850

[Peter Kasting, 2009-12-16 23:33:50]

LGTM, and I'm sorry I didn't think of this the first time.

[xiyuan, 2009-12-16 23:51:27]

On 2009/12/16 23:33:50, Peter Kasting wrote:
> LGTM, and I'm sorry I didn't think of this the first time.

This is not a normal case that people would know. :) I did not know that Hebrew
IME would inject keystrokes. With Hebrew IME active, right alt would generate
four messages: fake VK_CONTROL down, VK_MENU down, fake VK_CONTROL sys key up,
then VK_MENU up. And the fake VK_CONTROL sys key up triggers our logic to send
down a VK_CONTROL key up which triggers RTL layout. GetKeyState(VK_MENU) works
if user release Alt key the last but not when it is released before the Shift.
In that case, we got a VK_CONTROL sys key up with a clear GetKeyState(VK_MENU).

It's rare case though. Usually user would do Alt+Shift. And richedit does change
to RTL when user do a RightShift+RightAlt.