Implement drop-down menus

[TheBrokenRail]

• All motion (and sensing of object (except for preset stage and sprite1)) menus that have sprites in them don't show sprites
  (Was Using This iv VM with Sprites)
  
• Broadcast Menu new broadcast doesn't do anything
  
• Broadcast menu doesn't show broadcasts except the preset ones
  
• Sensing of block property menu does not show variables
  

[TheBrokenRail]

Added screenshots to demonstrate problem.

[TheBrokenRail]

I think this should be ready by the prototype cause menus need to work.

[tmickel]

Thanks for the screenshots - that should be helpful when this is implemented!

Regarding your last point:
The "squared" menus with block-colored backgrounds are intentional; no reporters can be dropped into those menus.

[TheBrokenRail]

What about circular menus with block colored backgrounds?

[tmickel]

Those shouldn't exist- either it's a mistake, or the color palette is too subtle to see the difference. Which blocks appear that way?

[TheBrokenRail]

some reporters, sensing of menus, variable getter

[TheBrokenRail]

Why is variable getter shadow round and list getter shadow square?

[TheBrokenRail]

I have a implementation for this that uses Blockly.Blocks.Sprite to hold sprite names and is set by vm on targets update, see closed PRs above.

[TheBrokenRail]

Note, At the current way menus are implemented the menus won't be updated until they are re-rendered.

[TheBrokenRail]

Though this could be solved by reloading the workspace, workspace to xml, xml to workspace:

Blockly.Xml.domToWorkspace(
    Blockly.Xml.workspaceToDom(
        Blockly.getMainWorkspace()
    ), 
    Blockly.getMainWorkspace()
);