Comment 76 for bug 954352

I looked again. See the wdiff of the Depends line after enabling wayland

Control files of package libgtk-3-0: lines which differ (wdiff format)
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Depends: libgtk-3-common (= [-3.6.2-0ubuntu1),-] {+3.6.2-0ubuntu2),+} libatk-bridge2.0-0 (>= 2.5.3), libatk1.0-0 (>= 2.2.0), libc6 (>= 2.14), libcairo-gobject2 (>= 1.10.0), libcairo2 (>= 1.10.0), libcolord1 (>= 0.1.10), libcups2 (>= 1.6.0-1), libfontconfig1 (>= 2.9.0), libgdk-pixbuf2.0-0 (>= 2.25.2), libglib2.0-0 (>= 2.33.14), libpango1.0-0 (>= 1.30.0), {+libwayland0,+} libx11-6 (>= 2:1.4.99.1), libxcomposite1 (>= 1:0.3-1), libxcursor1 (>> 1.1.2), libxdamage1 (>= 1:1.1), libxext6, libxfixes3, libxi6 (>= 2:1.2.99.4), libxinerama1, {+libxkbcommon0 (= 0.1.0~2-0ubuntu1),+} libxrandr2 (>= 2:1.2.99.3), shared-mime-info, at-spi2-core

We gain libwayland0 and libxkbcommon0.

libxkbcommon0 is in universe. Benjamin, do you want to talk to ubuntu-x about whether main inclusion would be feasible? Note that its description says this:

Description-en: library interface to the XKB compiler - shared library
 libxkbcommon aims at replacing xkbcomp, the XKB compiler.
 .
 UNSUPPORTED. This is an experimental library, and its ABI/API is likely to change
 on a regular fashion before it stabilizes, depending on XServer's and
 Wayland's needs in particular.
 .
 More information about X.Org can be found at:
 <URL:http://www.X.org>