940296 - [Debugger] should not change the scroll position in the js file when stepping (unless it's necessary)

Status: RESOLVED DUPLICATE of bug 950739

(DevTools :: Debugger, defect)

Description

[Julien Wajsberg [:julienw] (PTO -> Mar 16)]

STR:
* debug a file (I was remote debugging here, I don't know if this has an impact)
* setup a breakpoint and trigger whatever is needed to go to that breakpoint
* scroll up the page
* press the "step over" button

Expected:
* the page scoll position is not changed

Actual:
* the page scroll position is changed

Additionally, we see a huge flickering which is really unpleasant.

I think that as soon as the user scrolled, the scroll position should not be changed automatically. We could have a button to put back the scroll behaviour in "automatic mode" though, but all this should be controlled by the user.

Even in "automatic mode", the scroll should not happen unless the next position is too low (say: in the 5 last lines), and in that case it should position the scroll so that the next (now current) position is in the center, to keep the context of what has been executed before.

When pressing the "go back in automatic mode" button, we could reset the scroll as you're doing right now, putting the current position at the top of the screen ("top" could mean "in the 5th line").

Comment 1

[Girish Sharma [:Optimizer]]

Can you add a screencast of what you are observing ?

For me, if a line is in view, scroll is not changed until the current line becomes out of view while stepping over/in/out.

Comment 2

[Julien Wajsberg [:julienw] (PTO -> Mar 16)]

You're right, it seems to work correctly when we're not remote debugging. The issue is when we're remote debugging.

Tell me if you still need a screencast after this information :)

Comment 3

[Girish Sharma [:Optimizer]]

What do you mean by "Remote debugging".
Does using Browser Debugger to debug local firefox build count as remote debugging for your test case ?

Comment 4

[Julien Wajsberg [:julienw] (PTO -> Mar 16)]

I'm remote debugging a Firefox OS application using the App Manager.

I don't know the Browser Debugger but I'll try debugging the Simulator and see if this reproduces with it.

Comment 5

[Julien Wajsberg [:julienw] (PTO -> Mar 16)]

Same bug when debugging with the App Manager using the Simulator.

Another strange probably relaed issue: when I set a breakpoint in the file while I'm _not_ debugging, the scroll is reseted to scrollTop = 0 (ie: scrolled to the top). If I'm currently debugging, this is not happening.