PR: Make middle mouse button click on editor tabs close the intended tab

[steff456]

Description of Changes

• Wrote at least one-line docstrings (for any new functions)
• Added unit test(s) covering the changes (if testable)

• Included a screenshot or animation (if affecting the UI, see Licecap)

Add offset to remain the region of tab given an event and be able to close intended tab

Issue(s) Resolved

Fixes #12558

Affirmation

By submitting this Pull Request or typing my (user)name below,
I affirm the Developer Certificate of Origin
with respect to all commits and content included in this PR,
and understand I am releasing the same under Spyder's MIT (Expat) license.

I certify the above statement is true and correct: Steff456

[ccordoba12]

Nice job @steff456!

@dalthviz, please test this PR on Windows to see if it's working as expected there. I'll test this one on my KDE desktop too.

[dalthviz]

@ccordoba12 it works for me on Windows 👍

[ccordoba12]

@steff456, please don't forget to check if this works with a change in the scaling factor of your screen so we can merge it.

[ccordoba12]

@steff456, please don't forget to check if this works with a change in the scaling factor of your screen so we can merge it.

@steff456 confirmed with me that this PR works for her on macOS with different scale factors, so I'd say this is ready.

[ccordoba12]

Great work here @steff456!!