Selected text is deleted if another external editor is focused

[fidel-perez]

Brief summary of issue / Description of requested feature:

Selected text is deleted if another external editor is focused

Steps to reproduce the issue / Reasons for adding feature:

• Select some code in the editor
• Click in the keyboard "control + c" to copy
• Without deselecting or doing anything else, select an external window (sublime Text in this case, and I tested too with Obsidian.md editor, same thing)
• Then, the text selection in mudlet is deleted.

This happens consistently, always without exception.
It can be "undone" by hitting "control + z" 4 times.

• Another related behavior: Sometimes the selected text just disappears, even without swapping to another window. I don't know how to exactly reproduce this one, but it happens. It might be related to selecting text via double click.

Error output / Expected result of feature

For the text not to be deleted.

Extra information, such as the Mudlet version, operating system and ideas for how to solve / implement:

Ubuntu.
Current development branch of Mudlet, in particular, this one: #7120