31516 - Unable to create offscreen window OR unmapped XUL window

Status: RESOLVED FIXED

(Core :: XUL, defect, P3)

Description

[rhp (gone)]

I have a need to create a window for rendering mail messages before printing. 
We need to do this because we display messages as a XUL document which can't be 
printed directly. I was created an offscreen window, but that is no longer 
allowed and I don't think I can create an unmapped window from JS?

Help!

- rhp

Comment 1

[Peter Trudelle]

Why is it not allowed?  Don't we still create an offscreen window on startup, at 
least on Mac?
reassigning to danm, cc saari

Comment 2

[saari (gone)]

I prevent you from moving a window offscreen. What you really want is a window 
that isn't visible... which should work just fine for printing, correct?

Comment 3

[rhp (gone)]

Correct. An invisible XUL window that I can create from JS would be AWSOME!!!!

- rhp

Comment 4

[saari (gone)]

Oh bloody hell, this is probably a JS compliance issue

<sigh>

Maybe I need to put my sanity checks at a higher level.

Comment 5

[Dan M]

There's never been an interface for creating an invisible window from JavaScript. 
We could conceivably add one (available only from signed or chrome JS, of 
course), but that feels bad. Of course, allowing placement of windows offscreen 
is the exact same security issue. Chris, you plugged in coordinate sanity checks 
at a pretty high level, didn't you? I'm still trying to figure out what to do 
about this one.

Comment 6

[Dan M]

Navigator has always disallowed offscreen windows created from unsigned JS. We 
need to do the same thing, and consequently allow offscreen windows from signed 
JS. This implies applying saari's sanity checks to only size and position derived 
from the local store; that is, as window tag attribute values. Currently, I 
believe that code is in widget -- at a level too basic. This is all somewhat 
straightforward, but not critical. Adding "helpwanted" flag.

Comment 7

[saari (gone)]

I still need to move that sanity check code higher. It is slowly creeping higher 
on my priority list.

Comment 8

[rhp (gone)]

This is more critical than you might expect. For printing email messages, I 
need to render them in a webshell and then print after they are done loading. 
Well, this webshell needs to be offscreen or not mapped or the user sees it on 
the desktop. Is there anyway to do either one of these?

- rhp

Comment 9

[rhp (gone)]

*** Bug 37430 has been marked as a duplicate of this bug. ***

Comment 10

[Peter Trudelle]

nominating for nsbeta2, since rhp says it is needed for printing.

Comment 11

[Peter Trudelle]

[nsbeta2-], assuming you can actually print.

Comment 12

[Dawn Endico]

moving from architecture to browser product

Comment 13

[Peter Trudelle]

Mass-moving all nsbeta2- bugs to M20

Comment 14

[rhp (gone)]

*** Bug 46324 has been marked as a duplicate of this bug. ***

Comment 15

[lchiang]

nominate nsbeta3, polish.

Comment 16

[Peter Trudelle]

nsbeta3+

Comment 17

[Dan M]

You can move windows offscreen now, and create them there as well. To do it in JS 
you must have UniversalBrowserWrite privileges. Test case follows:

<?xml version="1.0"?> 
<?xml-stylesheet href="chrome://navigator/skin/" type="text/css"?> 

<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
        orient="vertical" autostretch="never">

<script language="JavaScript">
<![CDATA[
  var win;

  function createOnscreen() {
    win = window.open("http://www.mozilla.org", "_blank", "left=10,top=10");
  }
  function createOffscreen() {
    var left = screen.width + 10;
    var top = screen.height + 10;
//netscape.security.PrivilegeManager.enablePrivilege("UniversalBrowserWrite"); 
    win = window.open("http://www.mozilla.org", "_blank",
            "left="+left+",top="+top+")");
  }
  function moveOffscreen() {
    var left = screen.width + 10;
    var top = screen.height + 10;
//netscape.security.PrivilegeManager.enablePrivilege("UniversalBrowserWrite"); 
    win.moveTo(left, top);
  }
  function moveOnscreen() {
    win.moveTo(10, 10);
  }
]]>
</script>

<button value="Create Window Onscreen" onclick="createOnscreen()"/>
<button value="Create Window Offscreen" onclick="createOffscreen()"/>
<button value="Move Window Onscreen" onclick="moveOnscreen()"/>
<button value="Move Window Offscreen" onclick="moveOffscreen()"/>

</window>

(Note the commented out lines aren't necessary if this window is loaded from a 
chrome URL, which automatically has those privileges. (And actually, something's 
broken in moveTo() at the moment. This sample code doesn't even try to work when 
loaded from outside chrome.))

I'm not sure this will give you what you wanted. The act of making an offscreen 
window isn't seamless or pretty -- for one thing the current topmost window is 
inactivated. (Which you can fix with a focus(), but doubtless the titlebar will 
flash.) And Enlightenment, for one, disconcertingly switches desktops in the 
above sample when you execute createOffscreen().

We may have to -- ugh -- add some way to create invisible windows from JS 
(security protected, of course) if it comes to that. Meanwhile, enjoy your 
offscreen windows. I'm hoping, rather ineffectually, they'll be enough.

Comment 18

[Dan M]

Testing/confirmation note: the above XUL sample doesn't quite work: moveTo fails 
security checks in our new, more restrictive world. Change the patch to load 
about:blank (rather than http://www.mozilla.org) and it will work as expected.