Improved reliability of clicking on disclosure triangle

[FigBug]

I was still having issues clicking the triangle to open / close items. Now the hit target is the exact location of where the triangle is drawn.

[sudara]

hmm what OS have you been using? Wondering if it was a mac/win issue.

[FigBug]

I'm on macOS

[sudara]

macOS here too. Strange, I still wonder what the specific issue was, it was very solid for me.

Good call on having a disclosureRect and deriving bounds via event translation. Much better than the recursive parent stuff I stole from TreeViewItem.

This implementation has a couple glitches for me:

1. The item is suddenly selectable in a sliver to the left of the icon.

2. The right side of the icon behaves as selection vs. disclosure toggle. It should be a toggle right up to the first pixel of text.

Also, this is unrelated to your changes, but there seems to be a debounce glitch when toggling disclosure on non-selected item.

[FigBug]

Ok, I tweaked the hit test area

[sudara]

Pixel perfect! Thanks Roland!!