Slack64 Current Multilib XFCE
The GUI suspend / hibernate options (XFCE 4.10 Power Manager, XFCE 4.12 Logout Popup) do not work, whereas previously they did. The CLI pm-{suspend,hibernate} commands still work OK.
Also on my Acer laptop the XFCE 4.10 Power Manager shows "Adapter is online" irrespective of whether or not the adapter is online. Previously the battery percentage and estimated time left were shown.

By pure chance I still have a Slack64 Current Multilib XFCE updated up to and including Fri Feb 26 2016 available. In there the above problems do not occur. When looking at the changelog for the later updates the Fri Mar 4 upower #3 rebuild seemed like an obvious cause. So I fell back on the upower #2 build and lo and behold everything works again.

Hi, FWIW, in my case, on xfce with build 3 of upower-0.9.23 on slackware64-current, suspend works. My laptop has on-board graphics. Could it be that some application is still running on the desktop that prevents the suspend...

The Xfce Power Manager panel applet has an extra tickbox (in settings -> general -> appearance) "show system tray icon" and I turn that off (because the system-tray sits next to the applet on my panel-layout). That systray-icon always shows a cord with a plug (in my case) whereas the applet-icon indicates the status of battery vs online-&-charging. The applet-icon changes when pulling the plug... Could it be that on your acer you only have the systray-icon and not the applet icon visible?

EdIT: could setting the "presentation-mode" to 'on' cause this? Before, it never seemed to do anything for me, but I haven't tested this properly since all updates

Hi, I'm running slackware64 14.1. When running the stock 3.10.17 kernel, hibernation and suspend works perfectly.
I was going to report when I saw this post that 4.4.x and 4.5.0 kernels do not have proper hibernation and suspend. The applications get ``shuts down ` but not the hardware, the wifi is still on, X is not running but the screen is still not off. I have to shut down and reboot to have a working environment.

I still have to test my own custom linux kernel.

@brobr: I still use(d) the xfce4-power-manager (PM for short) 1.2.0 from XFCE 4.10 because its systray icon supports suspend/hibernate, whereas the PM 1.4.4 from XFCE 4.12 no longer does so.

PM 1.2.0 only has a systray icon. With upower 0.9.23 #3 the suspend/hibernate options are greyed out and no battery % is shown, whereas with upower 0.9.23 #2 these options work and a battery % is shown.
PM 1.4.4 has a systray icon as well as a panel applet. With upower 0.9.23 #3 both show no battery %, whereas with upower 0.9.23 #2 the systray icon still does not, but the applet icon does!

The suspend/hibernate buttons of the XFCE Logout popup do not give a discernable result with upower 0.9.23 #3, whereas with upower 0.9.23 #2 they work as expected.
In both cases the CLI pm-{suspend,hibernate} commands work as expected.

@jheengut: I am running 4.4.x kernels from rc5 onwards and never experienced the suspend/hibernation symptoms you describe. Maybe the fact that you run 14.1 and I run Current is relevant here.

Dunno, but this afternoon, as soon as the kernel-4.4.5 kernel is installed, I will test on slackware-current on my laptop.
Does this mean that suspend is not only dependant of kernel but the userland tools too?

@jheengut: I do not know about the kernel (though I think it is quite possible for this to be true), but certainly there is a dependency on the userland -- at least on upower, as this thread shows. Slack64 14.1 has upower 0.9.17, whereas for Current the problem arose with a rebuild of upower 0.9.23.