It's shifted downward to not overlap the menubar, since it's hard to make a child z-indexed below its parent.

It's a cleaner API IMO but ended up being a messy implementation...

These use a technique where the save/load functionality is passed from the component to its children via a function argument.  I opted for this rather than a higher order component because it is more readable and requires fewer intermediary components.

This could just as easily been done with a higher order component and would be happy to change it to that instead.

There is a performance implication since there is a function being defined in render. However the menu bar is not a highly re-rendered component, so I thought it would be ok in this case.

Sorry @carljbowman

Mostly to remove the repeated props

We have actual menu items now so the things that were menu items should be considered menu bar items

They open and close what more do you want?

The error message is included in the first line of the stack

While working on the menubar, I couldn't find the source of an error. This adds more stack info to the error messages emitted by the error boundary.

Updates include modifications to interaction states for the following: tabs, add menus, forms, and stage selector.

- Auditing color CSS and componet CSS to make consistent.
- Made a first pass of changes to increase contrast to elements that previously were problematic

It seems like there is some kind of touch action interference coming
from the blocks panel, where if you touch the tabs on a touchscreen
chromebook/chrome responsive mode, it does not select the tab if the
touch radius is overlapping the blocks panel at all. See gifs in PR for
more explanation. Fixes issue #1283, making chromebooks useable!

If an extension is loaded at project-load time, there won't be any
targets. In that case, `handleExtensionAdded` now skips target-specific
steps.

This change also adds a filter for JSON block info to support upcoming
block separators, which have XML but no JSON.

Resolves https://github.com/LLK/scratch-gui/issues/1713

Add a jest unit test for making sure the number is rendered out when
provided and not when not provided.