Make Sandcastle.addToolbarButton hide the highlight logic.
Merge pull request #1812 from AnalyticalGraphicsInc/hide-highlight-code

Make Sandcastle.addToolbarButton hide the highlight logic.
Fix #1797, with awareness of widget visibility.
Merge pull request #1814 from AnalyticalGraphicsInc/issue1797

Fix #1797, with awareness of widget visibility.