Intermittently, the Tab close button does not appear. When this happens, the tab text is also incorrectly aligned. See the attachment.

This happens even though the tab-closing-policy is ALL_TABS and closeable is set to 'true' for every tab.

I can reproduce this with a program that allows the user to create a new tab by clicking on a button.... when I click several times in a row, the problem occurs once every 2nd or 3rd run of the program.