Add Selected Fields Option button at the Top of Fields Pane

I have been waiting for years, but still wondering why Microsoft doesn't offer the option button to view 'selected fields' on any visual or page above or below the Search box in the Fields Pane, so they can all be seen at the top for easy use/changes, formatting etc.  At times I have 10+ data sources, it would be nice to not have to constantly expand/collapse these tables to look at or look for what fields are being used.

Thank you for all you do for us to make our jobs easier.

Nanc