Contributions to Vizia

I have recently made several contributions to Vizia, an open source desktop UI framework built in Rust, which aims to be easy to set up and declarative (meaning that the developer can declare that a value will always be equal to a variable, so when the variable changes, the UI automatically updates). My changes related mostly to the keyboard navigation, making the later integration of the AccessKit screen reader API easier. I've listed some of my changes below:

• Focus improvements - this PR added support for styling the focused widgets with an outline.
• Trigger buttons with keyboard navigation - which allowed the user to activate a button that was focused by pressing space. I discussed with geom3trik (the main developer) about if this should use the existing mouse down event or a new, more general TriggerDown event.
• Add lock focus to subtree - prevents the user from navigating to outside a dialogue menu, similar to the behaviour with the new HTML <dialog> element.
• Add arrow key support for Slider - this allows users to change the value in the slider with the arrow keys, with a configurable speed.
• Improvements to debug tree (i key) - added a debug utility for displaying the tree of widgets.
• Textbox improvements - added support for double clicking to select a word, and fixed some faulty behaviour when dragging to select a range of text. I discussed the desired behaviour with geom3trik and improved it appropriately before merging.