Keep the text selection (or the caret position if there's no selection) when the window is refocused

[GH01]

https://github.com/m417z/Textify/issues/17#issue-1118803330

• With the window open, I can trigger more than one button during the session (especially when I deal with a selection, not the whole text).
• I can switch between windows.

So please enhance it to keep the text selection (or the caret position if there's no selection) when the window is refocused.