Keep focus in symbol class table (symbology pane) when updating values via keyboard

[wayfaringrob]

Right now if you are trying to update labels for symbology using the Tab key, the symbology pane loses focus after updating each row. Focus goes to the attribute table -- highly undesirable. That means for each and every edit, you have to tab, wait, mouse over and click, enter the value, and repeat. It should just be tab, as is standard across almost all tabular data interfaces.