Tree editor does not show "+" and "-" buttons until window is resized
In Mac OS X only, the + and - buttons for completely collapsing and expanding
elements are not initially rendered when entering the tree editor. If the tree
editor window is resized or the bar dividing the lefthand and righthand portions
of the window is moved, the buttons appear and function normally.
#1 Updated by Jing Tao about 16 years ago
This is beause the buttons were not set prefered size. Different OS will render these button differently if no prefered size were not set.
So after setting the prefered size, this bug was fixed. I tested in windows, Mac OS and linux and it seemed every os can display them correctly.