Extension viewlet scrolls when navigating with tab

[bpasero]

Steps to Reproduce:

1. have a list with elements inside that have a tab index
2. navigate to an item that is only partially visible

=> you can end up in a very bad state where the height of the list is no longer proper

[bpasero]

@joaomoreno another related issue is that the order of DOM elements in the list is not the same order as visible, so that navigation with tab key yields unexpected results. Would it be possible to add a setting to have DOM elements in order? I do not expect a lot of notifications to show up, so I would tolerate a degrade in performance there.

[joaomoreno]

@bpasero We already established yesterday that this is not a bug in the list. Some element above the parent chain allows the scrolling to happen. We saw the very same thing yesterday in the notifications box.

Maybe file another issue for the order?

[joaomoreno]

There were two fixes here:

• Remove the height: auto, introduced by @ramya-rao-a; make sure removing it doesn't break anything. The height of the list always needs to fill its container: 100%.
• Prevent the monaco-scrollable-element from scrolling itself (it changes its own scrollTop property when navigating to hidden focusable elements) by resetting scrollTop to 0. @alexandrudima should this always be the case for the ScrollableElement class? Or is the list a special case since it implements its own scrolling using translate3d?

[bpasero]

@joaomoreno I created #44193 for the keyboard accessibility issue.

What is left for me to adopt to get this fix for the notifications? I guess some option to dock list items to the bottom instead of to the top?

[joaomoreno]

Yeah, sounds about right!

[alexdima]

@joaomoreno Yeah, this would happen when not scrolling using the regular scrollTop...

Browsers try to desperately reveal elements that gain focus... scrollTop could be changed for any element in the parent hierarchy for the element which gains focus, until the focused element is no longer occluded.

Here is my version of your listener: https://github.com/Microsoft/vscode/blob/93045738c3112e9b914581b038192b2cb3d4a453/src/vs/editor/browser/viewParts/editorScrollbar/editorScrollbar.ts#L87