Add shortcuts to tool tips in the palettes

There are many, many functions available in the palettes and elsewhere. Many of these are accessible via shortcut. Currently to find the shortcut you need to look it up in the manual, or in the Preferences > Shortcuts list.

It would be very useful to have the option to display the shortcut when the mouse flys over the element in the palette. This is already available for some items in the toolbars (e.g. selecting a voice), and it would be very beneficial for the palettes as well