Possible CharacterMap enhancements (easy)

[humdinger]

This is hrev29833.

A few possible enhancements:

1. If I scroll down in the character map on the right side, it'd be nice if the current position was reflected on the left "contents" view by updating the selected block "heading".
   
2. By moving the font selection into a drop down menu (to the right of the font size?) it would always be visible what font you're examining.
   
3. Is the menu item "Show private blocks" really necessary, is there a need to hide those?
   
4. Blocks that don't contain any characters could be greyed out (in the "contents" list to the left).
   
5. Left-clicking a character could increase its size (x2 ?) for detailed inspection.
   
6. The selected character could also be shown black on white in front of the "Code:" line at the button. This way you can be sure you didn't accidentally move the mouse to the adjacent character while taking your eyes from it.
   
7. CharacterMap should node-monitor for updated fonts.