Closed Bug 40901 Opened 20 years ago Closed 19 years ago

While mozilla is frozen, dropdowns are "always on top"


(Core :: XUL, defect, P3)

Windows 98





(Reporter: jruderman, Assigned: trudelle)



(1 file)

If mozilla freezes while a dropdown is dropped down, the dropped-down part 
stays on top of other (non-mozilla) windows.  I think this happens with crashes 
as well.

Steps to reproduce:
1. Load testcase
2. Pull dropdown down and wait for a second
3. Switch to another application and try to cover the dropdown

The testcase exploits bug 13350 (mozilla is unresponsive while running JS).
Hmm, well no testcase here, but a bit of js like:

function loopForever() {
  window.status = "looping now";
  while(true) {
setTimeout("loopForever();", 10000);

would exploit bug #bug 13350. However, I'm not sure that this bug isn't just
equal to bug #13350 -- there is no callback from js, which starves the
UI, which means that the popups never get a message to tear themselves down.

Are there other ways that mozilla can get into this state, and are any of them
not equivalent to a complete lockup? In other words, when the callback is 
implemented, this shouldn't be a problem anymore, no?

(BTW, this applies to both HTML Form Controls and to XPToolkit Widgets).
Depends on: 13350
Attached file test case
Oh yeah, actually attaching the testcase would have been a good idea :)

This bug wasn't meant to depend on bug 13350 -- it was meant to demonstrate 
another bug that happens during a freeze, using 13350 for the freeze.  Sorry 
for the confusion.
No longer depends on: 13350
Yes, but I'd argue that the solution to this problem is equal to the solution
to bug 13350 -- implement a callback into the DOM so that UI events don't get
completely hosed when JS runs wild. [That is, unless there is some other way
to get into this state that doesn't involve looping in JS (either directly or
There are zillions of ways to crash or freeze mozilla...

*** This bug has been marked as a duplicate of 13350 ***
Closed: 20 years ago
Resolution: --- → DUPLICATE
This is not a dup of bug 13350.  This bug is something that happens during 
freezes.  Bug 13350 is one my many exploitable bugs that freezes mozilla.
Resolution: DUPLICATE → ---
It's a duplicate because the UI thread is starved for events so the combobox 
never gets the event that tells it roll up the drop down. There is nothing I can 
do it fix this bug. Once 13350 is fixed this bug will be fixed too, so it is a 
duplicate. Please mark it as one. thanks
This bug won't go away when bug 13350 is fixed!  It happens whenever a 
crash/freeze is triggered while a dropdown is dropped down.

This bug could be marked as depending on bug 25472 (don't crash) and bug 30942 
(don't freeze), or it could be marked as WONTFIX.  Blaming a specific crasher 
for the problem isn't the right thing to do.

(What is it about native widgets that allows other windows programs to not have 
this bug?)
ok, well it isn't a bug that will get looked at until afer FCS.
Target Milestone: --- → Future
Fair enough.
Hyatt sez this sounds like view manager, but it is no longer a component.  Who
should get this, or should it be resolved as wontfix?
I think this is a won't fix. Mozilla really shouldn't be "freezing"
making it so
Closed: 20 years ago19 years ago
Resolution: --- → WONTFIX
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