Disable size containment for split handle

[krassowski]

Fixes jupyterlab/jupyterlab#14219

[JasonWeill]

Suggested change

	contain: style!important;
	contain: style !important;

Unless it's meaningful to have style!important as one contiguous token, adding a space would make this more readable.

[andrii-i]

Is using !important here OK because essentially we never want the style to be overwritten by anything?

[krassowski]

This is a good question. In JupyterLab it would be ok with the logic "we are overriding lumino and changing widget setting to not use strict containment in JS is not worth the trouble". But here we are modifying core lumino so maybe another fix by not adding contain: strict would be better. I will need to check if we can do so without breaking API.

[krassowski]

So instead of adding this style we should just remove this line:

lumino/packages/widgets/src/splitlayout.ts

Line 832 in 133d872

handle.style.contain = 'strict';

Thanks for questioning me - the identification of the problem was right but solution was wrong, another reason not to make PRs at 3am even if those are as simple as 2 lines :)

[krassowski]

Or rather we should change strict to style here.

[andrii-i]

No problems! I've searched for !important in Lumino before asking and it is used in couple of places in the codebase. Thanks for fix and explanations

[andrii-i]

Fixes the problem, side panel "split handle" now behaves in line with previous versions. Below is comparison of 3.2.9 where problem is not yet present (JupyterLab Light theme) vs current head-of-master with proposed fix applied directly to split handle css (JupyterLab Dark theme)

[andrii-i]

Let's merge this (I don't have access / rights to merge)

[andrii-i]

@krassowski wanted to ask what needs to be done to put lumino with #560 merged into jupyterlab? Is it something like lumino new release --> update jupyterlab dependencies?

[krassowski]

Yes. We have a few another PR on lumino which could be included in a new release.