669895 - [hang] Stuck at Print Preview "Progress:: Preparing..." dialog with onbeforeprint="alert('test')"

Status: REOPENED

(Core :: Print Preview, defect)

Description

[Martijn Wargers (dead)]

Attachment: testcase

Not a big issue, but something is not completely right in this case.
When going into print preview, an alert comes up and the 'Preparing' dialog stays there. After dismissing those dialogs, you get into the print preview mode, except, the page is not really print previewed, it seems.

Comment 1

[Jonathan Watt [:jwatt]]

What's currently happening is we open another tab for about:printpreview and the Print Preview progress dialog. Meanwhile back in the original document and its tab (which we can't see) there is an alert popup. That modal popup blocks the 'beforeprint' handler from returning, so the progress dialog in about:printpreview is stuck with no indication of why.

Comment 2

[Jonathan Watt [:jwatt]]

It looks like TemporarilyDisableDialogs[1] is what we would like to use to fix this, but that class is MOZ_RAII (stack class only) so we can't just add it as a member to AutoPrintEventDispatcher[2] since we sometimes store our instance of that class.

1. https://dxr.mozilla.org/mozilla-central/rev/c4ebc8c28a33b785dfbfa533810517cc707d1ad0/dom/base/nsGlobalWindowOuter.h#399
2. https://dxr.mozilla.org/mozilla-central/rev/5faab9e619901b1513fd4ca137747231be550def/layout/base/nsDocumentViewer.cpp#411