Some changes in area properties are forgotten

[Shad000w]

To Reproduce

• Open a module with several areas.
• Open multiple areas at the same time while using tabs feature. I tested with three, two should be enough.
• While having one area opened in current tab, select one of the other areas which you opened before and which tab is still available.
• Add or remove existing variables (I believe that every change except changing area name will trigger the issue).
• Save module. (This step is actually needless, however I wanted to show that not even saving will help avoid triggering this issue.)
• Now open the area which you edited. Open its properties and check if changes has been saved and notice that they weren't.

Specifics

• Build: 36-13
• Regression? No, issue related to new feature.

If needed, describe the bug