Resizing initiates hover actions

[tones111]

When resizing a window via dragging the edge mouse hover effects can be seen during the drag when a component moves over the position where the mouse was initially pressed. This is most easily seen in the button example where the button color changes while actively resizing.

This is likely related to the concerns of #38

[christolliday]

Thanks for the issue, turns out it happened because the component that updates hover state has to cache the mouse position and recheck what's there when the layout changes, but when you resize the window the mouse moves outside of the window and no positions are reported. Should be fixed by 2633650
The fix was to check for the CursorLeft event and set the mouse position that's used to check what is hovered to None.

[tones111]

Thanks for the fix. You've been making impressive progress. Hopefully I'll get familiar enough to make code contributions once the churn settles down a little. Really enjoying watching it progress and looking forward to see what it becomes. Thanks for all your hard work.