Possible race condition in SkillGUI class when removing a screen

[krisgesling]

Describe the bug There have been multiple reports of unexpected behaviour when removing pages from a GUI namespace.

Most recently in the Pairing Skill: https://github.com/MycroftAI/skill-pairing/pull/71#discussion_r730012240

As it's beyond the scope of the Pairing Skill it's been moved here.

To Reproduce Run the GUI stress tester Skill: skills-gui-stress-test.aiix.zip

To run the test: "run stress test one"

Expected behavior Adding and removing pages should operate consistently and be performed in the order in which they are requested.

[forslund]

Was this resolved through #3022?

[krisgesling]

Not sure, I haven't tested it deeply yet.