This is a simple engine that renders inputs and textareas with custom blocks in one sprite. Click on the input and type, click anywhere else to unfocus it. Up arrow is shift, left is backspace (in a textarea, right is scroll up, down is scroll down or enter). See inside and see the sprite "Graphics Handler" to see the code. ~ This doesn't have to be used, just thought I'd show everyone ~ The color scheme can easily be changed. There is a bug where you can keep typing past the end of a text area, but I can fix it (I just don't have the time).
Thanks to @-Rex- for PTE Ultra+ You can see this all in use in this project: https://scratch.mit.edu/projects/282753044/