Script editor area goes under other editor windows

[QbieShay]

Godot version:
3.0 beta2

Issue description:
If there are no matches in search&replace, the text area for scripts goes under the scene/inspector.
Removing search term in search&replace (so the "No Matches" red label goes away) fixes the issue, after switching to another view (2D/3D) and going back to script

Steps to reproduce:

1. Search for something that doesn't exist with search&replace
2. If the window is not wide enough, the "No Matches" label will overflow on the right, bringing the script text editor area along

[akien-mga]

CC @Paulb23 @ianb96 @volzhs

[capnm]

Something like this?
It would also be useful to display matches (or replaced) xy occurrence(s)

[kitbdev]

This happens in general when resizing the script editor when the find replace bar is open.

This also happens with the shader editor.
see #14812

[capnm]

The text in the animation editor has also overflow problems:

[YeldhamDev]

The code editor doesn't have this overflow problem in 2.1.4. Something changed in the 3.0 version.