Add Drag to Select a Group of Shapes

[Kevin Mullins]

Need to add the ability to drag from an empty space over a section of shapes and have those shapes be added to a group (just like Shift-Clicking works now).

• Implement Drag to Select
• Add Select All menu item and functionality.
• Add Select None menu item and functionality.
• Click an already selected shape to deselect it.

[Kevin Mullins]

Done.