SourceTree Beta 2.1.4.0 - able to see minimize maximize and cross

When clicking on the cross button(close) I'm noticing that while the button is closed down it is... un-hiding the hidden "Windows style" close button instead of just showing the SourceTree one.

This doesnt occur for internal pop-ups, only the full window

Additionally Clicking and dragging over the buttons in different ways can bring up the rest of the minimize/maximize/close buttons, which only disappear when the SourceTree buttons are hovered over after releasing the mouse button.

These buttons are clickable

Reproducing steps

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Click and hold on Close button, and drag mouse down

Clicking different parts of the button may bring up different hidden buttons

--apologies I can't seem to attach images, button is similar to those seen when googling
"windows 98 close"