You can revert to the old behaviour by editing the settings xml file at %appdata%\Grasshopper\grasshopper_kernel.xml
. Change this line:
<item name="Canvas:SpaceIsRadial" type_name="gh_bool" type_code="1">false</item>
to this:
<item name="Canvas:SpaceIsRadial" type_name="gh_bool" type_code="1">true</item>
There is no alternate keyboard shortcut at the moment.