Fix CONTAINER_PROJECT_SETTING_TAB_RIGHT option of EditorPlugin

[allenwp]

This fixes incorrect behaviour when using the CONTAINER_PROJECT_SETTING_TAB_RIGHT option with EditorPlugin.add_control_to_container.

Example:

add_control_to_container(CONTAINER_PROJECT_SETTING_TAB_RIGHT, control)

Before this PR:

After this PR:

[timothyqiu]

I guess this is actually a mistake in documentation. CONTAINER_PROJECT_SETTING_TAB_{LEFT,RIGHT} adds the tab relative to the "General" tab instead of relative to the entire list of tabs.

But the documented behavior is more intuitive and useful I think 👍

[KoBeWi]

CONTAINER_PROJECT_SETTING_TAB_RIGHT adds the tab relative to the "General" tab instead of relative to the entire list of tabs.

No, it adds it relative to the leftmost tab. If you add a tab to the left, the right tab will be added after your tab and before General.

[timothyqiu]

No, it adds it relative to the leftmost tab. If you add a tab to the left, the right tab will be added after your tab and before General.

Ah yeah, my interpretation of current behavior is wrong. My point is that the documentation was added three years after the implementation. So it's very likely the documentation is wrong.

[Repiteo]

Thanks!