Top bar improvements

[Rylern]

Address #10 by:

• Updating the combobox to reflect the currently-open page.
• Putting the top bar on one horizontal line.

[petebankhead]

I like the saved space (current screenshot below, for 'before' see #10 ) & especially how the selected jar updates to match the page.

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• Should the search bar be on the right, not the left? I was thinking left, to make it the most prominent input control.
• The min width seems quite larger - could this be reduced?
  • I think an HBox is being used for the title bar currently; did you compare this with a ToolBar? A ToolBar should make it possible to shrink further and add extra buttons to access options that don't fit, but I'm not certain if this would be a good or a bad thing.

Pinging @finglis and @alanocallaghan for their thoughts.