Also, if this is just an asthetic issue rather than a wasting a few pixels issue, you can go to View > Toolbars > Customize... and adjust the vertical spacing for the bitmaps on your toolbar buttons. The default vertical spacing is 0, but if you bump it up to 1 or 2, the sizes might match up better with your current context toolbar.
Also, also, there is an current context tool available. Go to View > Toolsbars > Customize... and select the "Categories" tab and then "Tagging". The combo box can be dragged onto any of your button bars. The disadvantage of this alternate current context tool is that it is not resizable, but it is much more compact.