SystemFont "Font Names" Editor UI deselects input box every keypress to search through fonts

[Jimmio92]

Tested versions

4.3.beta2

System information

Win 10

Issue description

Every character I enter into an array element in the Font Names property of SystemFont accepts the character, then deselects the box during what I suppose is a search for that font. This is fine behavior if you're pasting the name of a font, I suppose, but if you're typing it, it's a bit of a nightmare

Steps to reproduce

using the MRP, open the project, open the theme in editor, expand a SystemFont override, expand Font Names, attempt to type "Source Code Pro" into said box or any other font name.

Minimal reproduction project (MRP)

systemfont-mrp.zip

[Calinou]

This is likely because _notify_property_list_changed() is called every time the property changes, which causes an inspector rebuild and therefore the LineEdit losing focus.