DevTools is sometimes obscured by web page

That is, the "envelope viewport" sometimes only moves up and overflows when open DevTools, while blocking part of the DevTools view, but it does not shrink as normally.

Note that if you change the size of the entire browser window at this time, the "envelope viewport" will switch between different specific specifications normally.

But if you just change the size of the DevTools view, the "envelope viewport" only moves up and down, but does not scale.

Not sure what triggers the issue, but it exists in both TB13.x and TB14.0.2