Defaults to 153% (pavucontrol reports 11.08dB)

for implementing pa-specific settings.

Style is based on the pulseaudio logo, svg is retained
in the repo for easier maintenance, png is installed.

Didn't seem to do anything and was producing a lot of warnings

Same fix as in:
http://git.xfce.org/users/eric/xfce4-power-manager/commit/?h=gtk3&id=4329d2601a35ccd2a48a509d9027b3a5707b3e4b

Seems like creating/destroying menus leaks memory.

GdkEvent coordinates should be refer to GdkWindow and indeed
in Gtk3.14 that is the case so no extra translation is needed.
However, in Gtk3.12, the coordinates refer to the slider widget,
even though it has no GdkWindow associated with it.
TBC if there is a better way of handling this, but Gtk version
checking works well.

This change was ported from libido upstream:
http://bazaar.launchpad.net/~indicator-applet-developers/ido/trunk.15.04/revision/187

Since symbolic icons are usually only 16px, the size steps
help to keep the icon sharp.

based on the widget's padding and border instead of
an relying on an arbitrary value.

(gtk_image_menu_item deprecation warning to be ignored)