Improve accessability: Adjustable color contrast and keyboard accessibility

Expected Behavior

Scratch beeing user-friendly to kids with disabilities: Color blindness, blindness or limited movement

• let kids adjust the colors of scratch blocks according to their needs or have a high-contrast mode button
• make the blocks keyboard accesible

Actual Behavior

• Some of the colors of scratch block have a low contrast ratio (White on yellow for events)
• Blocks are not keyboard accessible

Interesting post on this here:
https://scratch.mit.edu/discuss/topic/279211/?page=12

Okt. 7, 2018 02:19:09 - RobotBopper
Scratch Accessibility for Low-vision and Blind Users
Hello. I am blind, and I am required to use scratch for my computer science class. I have some ideas to make scratch more usable with screen readers. Screen readers do not use the mouse, but you use the keyboard to navigate. The up and down arrow keys are used to move around on a page, and tab and shift tab are used to move through controls like buttons, links, edit boxes, and other items that let you do something on a webpage. If the parts of the screen could be divided into sections that a screen reader could recognize, that would make it a lot better. I can not move left and right on the screen. If I use up and down arrows, it automatically moves to the right, and it mixes parts of the blocks in the list of blocks with the ones that I have already put in. Here is an example of how it reads the blocks.
play
move
sound
10
meow
steps
until
done
I can't use tab to move through blocks either, because the screen reader doesn't recognize them as interactable controls.
Putting in blocks is hard too. Since I can't drag and drop, I can't actually add blocks. My idea is to add better labeling to the blocks, and make a keyboard system for putting blocks into the program. For example, space would let you see what the block would do in the program, and enter would actually put it into the program
.
For anyone that would like to download NVDA and see how it works with scratch and what commands blind people use to navigate their computers and the internet, the website is www.nvaccess.org. I hope this helps.

The issue does not identify files, tests, or entry points. Begin by locating the block color-rendering and block interaction code, then review the requested high-contrast or adjustable colors and keyboard navigation against the described screen-reader use cases; done should include accessible colors and keyboard-based block interaction.