[tor-bugs] #11194 [Tor bundles/installation]: Tor Browser detected screen size is different than Firefox

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#11194: Tor Browser detected screen size is different than Firefox
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 Reporter:  joebt                     |          Owner:  erinn
     Type:  defect                    |         Status:  new
 Priority:  major                     |      Milestone:
Component:  Tor bundles/installation  |        Version:
 Keywords:  Tor Browser, screen size  |  Actual Points:
Parent ID:                            |         Points:
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 Now using TBB 3.5.2 (Windows).
 I see "odd" (unusual) screen sizes reported / detected for TBB browser
 tests - at several sites (browserspy.dk, panopticlick, ip-check.info).
 Like showing 1920 x '''966''' (or '''963''',etc.).  This stands out like a
 sore thumb.   It is also affected in Windows by 2 system settings.

 1) When Windows system DPI * IS * set @ default 96 DPI.
 2) When the system DPI is NOT the default value (many users MUST set DPI
 larger, to read various screens. Ex.: both Windows' & apps' UI & Help
 screens, etc.

 __With system DPI @ 96__.  At the same time as testing TBB, regular Fx (no
 "privacy addons" hiding / spoofing browser data), all the test sites show
 1920 x 1080 for Fx.

 That is w/ EXACT same toolbars & other UI elements displayed in both
 browsers, where test sites show __odd values for TBB__ - 1920 x '''966'''
 (or what ever).  Not good.

 The "966 or 967" '''TBB''' screen height (or whatever odd number),
 '''turns out to be''' the height for the part of browser window, beginning
 just below the browser navigation bar, down to the top of "Addon Bar."


 However, in __regular Fx__ , the test sites  show screen size of the
 '''full''' monitor: 1920 x '''1080''', not just the "usable display area"
 of the browser pane (the part of browser window where websites actually
 display).

 __2nd Case:  When system DPI is NOT at default 96.__

 Not sure anything can be done, so sites monitoring screen size (TBB or any
 browser) don't see odd sizes, when the system DPI is @ NON-default value?
 But, even in that case (say, DPI -  110), the test sites STILL show
 different screen sizes __for TBB vs Fx __(27).  So all Fx & TBB users that
 set the system DPI @ 100, 110..., sites that check will see different
 values for TBB vs. Fx.  Again, not good.

 See comments 10 & 11:
 https://trac.torproject.org/projects/tor/ticket/7256#comment:10

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/11194>
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