Collapse debugger panel when disabling debugger

[yanmulin]

References

Addressing the issue: #13018

Code changes

listen to Debugger terminated event and collapse the debugger panel if it is visible.

User-facing changes

Before

After

Backwards-incompatible changes

None

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[fcollonval]

Thanks for opening this PR @yanmulin

Would you mind not closing the tab if multiple debug sessions are active (see screencast) or place this behind a setting?

[fcollonval]

I don't think we can figure out if there are other opened widgets with an active debug session. @afshin is that correct?

[krassowski]

Performance and UX wise:

• closing the panel will cause layout shift and freeze apps if there are too many nodes (not that big of a problem with windowed rendering, but if someone has huge SVG on screen it still might happen)
• for the same reason it will shift the content of all open editors/widgets, possibly leaving the user scrolling around to find where they were.

So ideally I would see the behaviour as switching to most recently used non-debugger sidebar widget on that side first and only if debugger is the only tab collapsing the right sidebar.

I'm not sure how feasible it is though.

[yanmulin]

@fcollonval A quick solution is to add a global variable to track the number of active debugger sessions. It increments when a session is started and decrements when a session is stopped. But not sure if it is a good idea.

[yanmulin]

@krassowski Couldn't trigger the layout shift on my side with a random big SVG found online. The cells just expand horizontally. Is that because the SVG not big enough?

[fcollonval]

A quick solution is to add a global variable to track the number of active debugger sessions. It increments when a session is started and decrements when a session is stopped. But not sure if it is a good idea.

I agree this is not an elegant solution - let's add a settings for this new feature. Do you need pointer for that?

Couldn't trigger the layout shift on my side with a random big SVG found online. The cells just expand horizontally. Is that because the SVG not big enough?

I think @krassowski was making a general comment that changing the width of a notebook will trigger style recalculation (and layout shift as the content distribution will change). This can freeze the UI if the notebook is large and/or contains highly complex views.

[yanmulin]

@fcollonval added a setting option.

[fcollonval]

Sorry for the late feedback @yanmulin.

Would you mind accepting the suggestion to make the settings follow the format name?

[krassowski]

@yanmulin here the layout shift has two meanings:

1. browser's need to re-compute the layout after a DOM/CSS change that could have shifted the layout
2. user-perceivable movement of elements

I mentioned both together, but you do not the (2) to have the (1). The performance consequences of layout shift in the sense of (1) are more severe when there are many nodes; SVG visualisations can have thousands or even millions of nodes, but this is not a precondition of layout shift occurring.

Here is an example of (1) - in visible in the debugger and (2) - visible because the print output with expanded/collapsed side panel takes either one or two lines:

Even if we remove the print() call, the layout shift in the sense of (1) still occurs:

[fcollonval]

Thanks @yanmulin

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[fcollonval]

@meeseeksdev please backport to 3.5.x