Unable to edit subtitles in the new Text window without closing and reopening it
I have this bug at least once every time I sit down to transcribe some subtitles to a timeline. I usually have the Text window up on my second screen and then work my way through the video, pressing the plus sign icon in the Text window, and typing in the subtitles one by one. At seemingly random times during this process I get this bug where the Text window just locks up. The program itself isn't crashing or anything, it's just that I can't click on a subtitle in the Text window to edit it, there's just nothing happening when I do this. Sometimes it's enough to click somewhere else on the timeline, and then back at the subtitle on the subtitle track, to be able to select the text and edit it again, and sometimes I have to close the Text window and open it again before it releases the lock. So far, nothing serious has happened due to this, it's just a nuisance.

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Alexander Riss commented
Thank you for reporting this issue! Premiere Pro 15.4 includes an improvement where this state should no longer happen (unable to click parts of the panel)