Adds unit tests for this HOC.

Use PureComponent instead since it is a simple shouldComponentUpdate check now.

Forcing the playhead onto its own painting layer removes an expensive composite with the waveform. Animate using transforms instead of left prevents layouts of the rest of the page while playing a sound.

The waveform component was being re-rendered while the playhead changed, which is a costly operation because it has to calculate the full svg path data string.

Also use white as the background since it gives the same impact and will not look bad if the filter isn't applied or takes a while to be applied

We were emitting drops when getMouseOverIndex was null, which could happen either when the drop is outside the container, or there were zero boxes to check for ordering. Treat these two cases separately, and continue to not emit drops when outside the container.

This reverts commit 97f8eb63, reversing
changes made to 2e017f06.

See #4382 for more info about why, and what we need to follow up on it

The previous change that made the images laid out using absolute meant that the close button was layered below the sprite image, making it now clickable

On some projects, the sprite image changes frequently, which can cause global layouts and paints if we arent careful. Use the same absolute positioning strategy from the sprite library animations to contain layouts to the sprite image itself

There was a useability issue discovered in testing where trying to trim a sound to be of zero length would fail, but just leave the trimmers active. Clear them out, since the trim is invalid

This is used because the sortable drop is also used for general dropping as well as sorting drop, so you need to be able to drop into a sortable list that does not contain any items.

Make the corresponding reorder code be more careful to check if there is a newIndex.

On slow machines it was possible to double click record before the chunk of samples had been processed, causing zero-length audio buffers

Discovered this while trying to pass other props to the stage wrapper, we were not passing isRTL to the stage wrapper, causing ask/answer bubble to not display the right direction.

https://github.com/LLK/scratch-gui/pull/4312 had a function name conflict with the existing code. This change fixes that by renaming the conflicting function, and removes redundant code.

Move the onClick handler to the overlay wrapper so that the whole stage is clickable to start the project instead of just the green flag button

www needs to know when a project finishes loading so that remixing can be disabled while the project is in a state that cannot be remixed.

Browsers other than IE will be allowed to load the GUI.
However, if there is an error, the error boundary will display an unsupported browser message recommending they update to the latest version of a supported browser.

For the purposes of this PR, ‘supported’ means you can load the gui (anything other than IE), and recommended is just the browsers that meet our minimum requirements for Chrome, Firefox, Edge and Safari.

Fixes useability issue where the drop area was too small, and you couldn't see it.