Update event modifiers on drag and drop events.

[castano]

In order to detect if any modifier keys are being pressed at the end of a drop event.

[floooh]

This is a good change, but I'll need to check if this fix is also needed on macOS and Linux.

[castano]

I don't know about Linux, but this certainly needs more work on MacOS. There's no NSEvent object available in the drop event handler, so it wasn't immediately obvious how to update the modifiers. It should not be hard to set these based on the most recent value, though.

[floooh]

Starting to look into this now.

macOS seems to have a class-method (aka static method) on NSEvent which provides the current event mask without requiring an actual event object: https://developer.apple.com/documentation/appkit/nsevent/1535211-modifierflags?language=objc

[floooh]

I'm doing a few slightly related fixes in my merge-branch, notes to self:

• set dx/dy to zero in SAPP_EVENTTYPE_MOUSE_ENTER/LEAVE:
  • macos
  • emsc
  • linux
  • win32
• set mouse-pos in SAPP_EVENTTYPES_FILES_DROPPED:
  • macos (previously this was the drag-start pos outside the window)
  • emsc (was already working)
  • linux (was already working)
  • win32 (was already working)
• dx/dy should be zero in SAPP_EVENTTYPES_FILES_DROPPED:
  • macos
  • emsc (was already working)
  • linux
  • win32 (was already working)
• set modifier keys in SAPP_EVENTTYPE_FILES_DROPPED:
  • macos
  • emsc
  • linux
  • win32 (already in PR)

...hmm, I can't find a way to get modifier key state in Xlib. The dropped-event doesn't have this info, and polling the current keyboard state always returns that no keys are pressed. Added a fixme-comment for now, but this might not be a feature to rely on in cross-platform apps.

[floooh]

Ok merged. Many thanks for the PR!

[castano]

Awesome, thanks!