33438 - Multiple monitors: JS GetWidth/GetHeight return incorrect values

Status: RESOLVED INCOMPLETE

(Core :: XUL, defect, P1)

Description

[guldgb]

From Bugzilla Helper:
User-Agent: Mozilla/4.0 (compatible; MSIE 5.0; Mac_PowerPC)
BuildID:    200003240

It doesn't use the display manager to get the screen width, it uses the grey region. When it tries to position a 
window on the screen, it does it relative to the space that all monitors take up, rather than a single monitor.



For example, a JavaScript that tries to calculate teh center of the screen will do so by getting the width and the 
height, and calculating the center. Under Netscape 4.x and IE, this will be a good calculation, resulting in a 
centered window on the parent window's screen. Under Mozilla, the window will be centered across the two 
screens.



Also, this makes the default window position wrong. it appears on the second monitor rather than the main 
monitor. In my case, the second monitor's top doesn't align with the main monitor's top, so the title bar isn't 
even accesable on the second monitor (you can only see the bottom half of the window).

Reproducible: Always
Steps to Reproduce:
1. Run a dual monitor system.

2. Use Mozilla. Try using JavaScripts that get width and height; bad values will be returned. Also try opening 
preference dialogs and such, they get centered wrong.

3.

Actual Results:  Windows appear centered wrongly; JavaScript's don't get screen coordinates properly.



A JavaScript that tries to make the browser window the full size of the screen would try and make a window 
that spans all visible screens.

Expected Results:  Mozilla should be placing windows on the main screen (or the screen of a parent window, 
as the case may be). Also, calculations for screen height and width should be based on the parent screen of a 
window, not the combined width/height of all screens (the grey region bounding box).

Comment 1

[Gervase Markham [:gerv]]

[e-mail] - do recent Mozilla builds still have this problem?

Gerv

Comment 2

[Gervase Markham [:gerv]]

Reporter sez:

"Yes. I checked the nightly build (5/5/00). You'd have to set the window 
position based on the GDevice (graphics device) on the screen that you want 
to center it on.

So if you want to center the window on the main screen (the screen with the 
global menu bar; typically what you want for dialogs and windows that are 
popping up for the first time), you get the GDevice record for the main 
screen (easy to do), check its bounds, and base the window position on that.

Also, when opening with a window position saved from disk, you should check 
if the window position is still valid (within the current bounds). Mac OS 
8.5 has a Window Manager function to let you do this easily. The thing is, 
the user may have disconnected or rearranged their second monitor since the 
last time they used Mozilla.

If the user had a window on the second screen (screen coords -500, 50), and 
then they later start up mozilla with only 1 monitor (so -500,50 is now an 
offscreen coordinate), the window won't appear onscreen and the user won't 
see it or be able to access it.

I haven't tried it, but if you're not checking that's likely what's going to 
happen. Check out the "Display Manager" and the GDevice stuff in Quickraw 
chapters of Inside Mac for thorough info.

You can send future questions to [e-mail] for more prompt 
responses."

Confirming.

Gerv

Comment 3

[rickg]

Don -- multimonitor support is yours, right?

Comment 4

[verah (gone)]

Reassigning as per Don

Comment 5

[saari (gone)]

Thanks for the analysis, it makes fixing the bug easier! I'll try and get this
into M16.

Originally we didn't have a JS exposed API for iterating over multiple monitors,
so we need this behavior to support multiple monitors at all. We now have that
API so we can revert this to the correct behavior.

Comment 6

[Peter Trudelle]

Moving all bugs that are not dogfood+, nsbeta2+,features, or nsbeta2- to M21

Comment 7

[saari (gone)]

Correct multiple monitor support is a must for beta3

Comment 8

[Peter Trudelle]

nsbeta3-. Affects few users on few web sites, not worth the time/risk.

Comment 9

[Gervase Markham [:gerv]]

[e-mail] - I don't know if your last comment was automated, but 
it's inappropriate. This bug, as far as I can see, affects _all_ 
multiple-monitor users on all websites, in that the window positioning will be 
wrong. Could you have another look here?

Gerv

Comment 10

[Peter Trudelle]

My remarks are sometimes mechanical, but never automated ;-).  Inappropriate?  I
don't see how, although perhaps the 'few web sites' was incorrect. Users of N6
on multiple monitor Macs are a tiny fraction of our userbase, we have very
limited time, so are focussing on bugs that affect all or most users. For Mac,
this means things like getting the MTBF above 30 minutes, or improving the
dreadful perforamance.  If we have time left, we can re-consider this bug. We
would welcome a fix from anyone who has time to fix it now.
qa->jrgm

Comment 11

[Mike Pinkerton (not reading bugmail)]

what is still broken here?

Comment 12

[Marcia Knous [:marcia]]

nominating for dogfood (from sdagley's list of bugs that are good candidates for 
our next release) 

Comment 13

[Peter Trudelle]

Dogfood?  Who is blocked from using the product because of this bug?  

Comment 14

[saari (gone)]

CC'ing danm because I believe he killed all of these issues by revamping a pile
of code (yeay!)

Comment 15

[Dan M]

Somebody with the hardware needs to verify. When last I left multiple monitor 
world, it was pretty well behaved. It generally thinks in terms of the one 
monitor the current window is on or mostly on, which should fix the problems 
described here. But I'm prepared to believe there are broken edge cases I didn't 
look for.

Comment 16

[R.K.Aa.]

similar: bug 62395, bug 101103, bug 149608. Dups?

Comment 17

[rkc]

I just ran into this problem on 1.3 on a Mac (OS X), so the problem is still
there, and is not (I believe) just limited to javascript commands.

Here's a test case:
Open Mozilla on a main monitor that is larger than the secondary monitor.
Open: http://www.ece.cmu.edu/c3s/raid2003/authors.html
Put this page on the smaller, secondary monitor.
Click on "instructions" towards the top of the page.  This will open a new
window, but the window will be sized for the main monitor, even though it will
appear on the secondary monitor.  Note that the top and bottom of the window is
cut off.

Comment 18

[Michael Kraft [:morac]]

There is still a case where this is a problem.  It seems if one checks the JS shortly after startup, they return the size of the first monitor even if Firefox ends up being restored on the 2nd one.  After the window is restored, the correct values are returned.