[Bug 1572331] Re: GtkPlug scaled to half the expected size on HiDPI screens + zesty debdiff

[Michael Terry]

Thanks Francesco and marmuta!  I've uploaded your debdiff to zesty,
Francesco, with only one real change: added some DEP3 tags to the patch
to point at this bug and upstream.

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Title:
  GtkPlug scaled to half the expected size on HiDPI screens + zesty
  debdiff

Status in GTK+:
  Confirmed
Status in gtk+3.0 package in Ubuntu:
  Triaged

Bug description:
  Hi,

  Marmuta wrote a patch for this issue, that I applied to the gtk+3.0
  package shipping currently in the development version of Ubuntu zesty.
  You will find the corresponding debdiff attached to this bug thread.

  Marmuta performed tests with org.gnome.desktop.interface scaling-
  factor = 2 , where few issues are left for Onboard on hidpi screens,
  that are not related to gtk, but rather to unity-greeter or gnome-
  screensaver. He did not notice any issue with scaling-factor = 1.

  Can a sponsor please review the debdiff?

  Thanks in advance.

  Francesco

  =============================================================================
  Original description:

  See attached screen shot. Blue is a GtkPlug, black is a GtkSocket.
  Source code below.

  What I expect to happen is that the GtkPlug has the same size as the GtkSocket.
  What actually happens is that GtkPlug only covers a quarter of the area of the GtkSocket.

  Impact: Onboard on HiDPI displays is near unusable at login and lock
  screen, aka unity-greeter and gnome-screensaver. Original bug report
  here: https://bugs.launchpad.net/bugs/1562734.

  Steps to reproduce:
  - build plug and socket samples from below
  - set display scaling factor to 2
    System Settings -> Display -> Scale for menu and title bars = 2
  - run  ./socket $(head -1 <(./plug))
  -> blue GtkPlug is too small, it should cover all the black

  - resize the window
  -> at smaller sizes the scaling suddenly corrects itself, at larger ones it's wrong again

  ProblemType: Bug
  DistroRelease: Ubuntu 16.04
  Package: libgtk-3-0 3.18.9-1ubuntu3
  ProcVersionSignature: Ubuntu 4.4.0-18.34-generic 4.4.6
  Uname: Linux 4.4.0-18-generic x86_64
  ApportVersion: 2.20.1-0ubuntu2
  Architecture: amd64
  CurrentDesktop: Unity
  Date: Wed Apr 20 01:48:50 2016
  SourcePackage: gtk+3.0
  UpgradeStatus: No upgrade log present (probably fresh install)

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