Fixed exception when expanding a folder
Fixed selection when expanding a folder. Triggers less "selection change" notification when expanding a folder.
Merge pull request #257 from dinhviethoa/256-fix-exception-selection-notification

256 fix exception selection notification (fixed #256)
Build version 0.0.12
css hover changes
Merge pull request #261 from dart-lang/css-selections

css hover changes
Merge branch 'master' into context-menu
review comments