Extended keys through RDP

[mgmartel]

I have been working more with RobotJS via RDP, which has been working great so far.

However, keys with an extended scancode (most notably, media keys) were not sent through correctly with the change from PR #151. To get extended keys to work, the flag KEYEVENTF_EXTENDEDKEY needs to be set in keybd_event (docs).

I could find no reliable way of querying the OS which keys are extended, so I looked in the src of FreeRDP/FreeRDP (here), because they have a similar issue.

All the keys that should have an extended scan code are now triggered with the KEYEVENTF_EXTENDEDKEY set. So now also media buttons, volume buttons, keypad, etc. work with RDP!

Links:

• FreeRDP Wiki on keyboard handling in RDP (very informative) https://github.com/FreeRDP/FreeRDP/wiki/Keyboard
• SO: "Can't trust MAPVK_VK_TO_VSC_EX" https://stackoverflow.com/a/30485060
• MapVirtualKey[Ex] doesn't specify extended scan code: http://www.setnode.com/blog/mapvirtualkey-getkeynametext-and-a-story-of-how-to/

[octalmage]

This is awesome! Thanks a ton for getting this fixed. Ill let @Deltatiger review this if he has time. I know the rdp stuff would be hard to test, so I really only care if this affects normal users.

[Deltatiger]

@octalmage This looks good. Just got my old system set up and tested it with actual RDP. I could only test a few keys but it worked.
I do not think there will be any issue with this commit affecting normal users.

[octalmage]

@Deltatiger awesome thanks a ton! I'm putting together v0.4.0 of RobotJS, this is going to be a great release.