Unfortunately UPower does not differentiate between desktop and laptop
systems so we decide that it's a desktop if it:
 * is not a UPS
 * does not have a battery
 * does not have a lid
In this case we show the "ac-adapter" icon for the systray and the
"ac-adapter-symbolic" icon for the Xfce Panel Plugin.

Before the "battery-missing" icon was shown, which is what UPower
reports for the display device.

DEVICE_STATE_UKNOWN means that there is no battery available.

Signed-off-by: Christian Hesse <mail@eworm.de>

The systray apparently can't use the dbus inhibt interface at all,
so use a direct call to get the list of inhibitors to display in
the menu.

Otherwise we may end up waiting for another part of xfpm that
hasn't loaded yet.

This patch now displays the applications that are inhibiting xfpm
from doing power management in the plugin/systray menu.

Found a couple spots where we inadvertently leak memory.

Signed-off-by: Eric Koegel <eric.koegel@gmail.com>

This brings back the about dialog for the panel plugin and updates
it for the newer stuff required by GTK3.

The property /xfce4-power-manager/show-panel-label has to be added to the channel
xfce4-power-manager as INT. Then you can set the value from 0 to 3, where
0: hides the label
1: shows the percentage
2: shows the remaining time and
3: shows time and percentage.

The format is not configurable for now and the label is hidden when UPower reports
the status of the display device as "fully charged".

In deskbar mode, the button takes up too much vertical space and is not
a square. Setting an extra resize request for the button fixes it.

This reverts 0dd1196b
and adds an additional check for UPower returning "" for the icon
name.

This fixes the panel icon on a desktop system with no battery
devices.

Regression of commit f6ceafb1

and always make sure to have an icon name,
even if UPower decides not to return one

macro "g_return_if_fail" passed 2 arguments, but takes just 1.
Patch provided by Poma.

I assume this is for devices UPower doesn't know anything about?

Per the 4.14 roadmap, Upower 0.99 is the new minimum so drop support
for older versions.

Drop old glib and xfce4ui version checks that aren't required
anymore.

It won't support GTK3 in the LXPanel. It's suggested to either
keep using the 1.4 branch or to use the systray icon once again.

After a discussion with Mattias Clasen and exploring alternative
options, we decided to switch back to GtkImageMenuItem as it works
best for what we want here.
In order for people to be able to compile without warnings, the
relevant parts have been wrapped in G_GNUC_BEGIN_IGNORE_DEPRECATIONS.