[Marketplace] Can not open template page/block when using double click

[milosmih92]

1. Select Templates gadget > TemplateRoot
2. Double click to open a template is listed under lower pane

Expected: Above template page/block should be opened well
Actual: Nothing happens, can not open by double click. User has to select "Edit" option from Options context menu to open page/block template

[milosmih92]

This is enhancement because we will need to change whole DOJO widget to support this, this will be fixed in next version.