Should there be a transition to ease out the cell toolbar rendering delay?

[krassowski]

Problem

Cell toolbar rendering takes time. This leads to blinking when switching cells

Before	After https://github.com/jupyterlab/jupyterlab/pull/16291

Proposed Solution

Note: the gifs below do not reflect how the transition looks in real life - unfortunately my recorder has a bit choppy framerate

Add some transition, for example opacity (here 150ms ease-in-out):

Slide in seems too aggressive with 200ms ease-in at 100% translation

but at 50% it looks bearable:

Additional context

None

[brichet]

Thanks for opening this @krassowski