Clear All History isn't fully visible

The Clear All History Window is not fully visible(screenshot above) when I first open it however, when I close it and open it again, the window is fully visible.

So each time if I want to clear my browser history, I have to close the first window and open it the second time to view the full window.

Browser Version:
Firefox Quantum 65.0 (64-bit)
Mozilla Firefox for Ubuntu
canonical - 1.0

Please report Firefox bugs on Bugzilla: https://bugzilla.mozilla.org/