Create a "ghost" tab on the options panel of MSA View

Create a mechanism in the source code of options pannel that allows to add "ghost" tabs
The "ghost" tabs add functions to other tabs. The "ghost" tabs are always shown on the top of the layout of the tab. A "ghost" tab does not have its tab button.
Such mechanism allows sharing function among tabs.

Using the mechanism, implement sharing the reference sequence selection function among the "general" and the "highlighting" tab.