Solution
On the log in screen, disconnect from the network, then re-connect. There should be a notification bubble showing up to inform you that you are connected.
After logging in, the MWM hints work without a hitch. I suspect this has to do with X's internal networking infrastructure.
Assumptions
- That this solution works for:
- Tiling window managers other than i3.
- Systems other than Ubuntu 14.10
- Systems running Desktop Managers other than Ubuntu's version of lightdm
- 32-bit systems
- Systems connected via WiFi
- Systems not on a network
Observations
Contrary to what the question says, alternating between different kernels does not actually affect whether MWM hints work correctly. Through many tests, I've confirmed that there is no correlation between the kernel version loaded and whether MWM hints decided to work
So far, getting the "connected to network" message in the lightdm login screen seems to always coincide with MWM hints working post login. This has been tested fairly rigorously, and is the currently accepted solution.
- This would imply a correlation between the network controller and MWM hints. Which could make sense, considering that MWM hints deal with Window Managers, which in turn deal with Xorg, which is a display server that uses the network infrastructure to send messages around.
Update
- I have recently removed lightdm from
/etc/init.d(as well as its .conf file), switched to dwm, and changed my image viewer to sxiv. I've also added myself to some additional groups in/etc/group. As of these changes, I've noticed that I no longer have to do the above "network trick" to gain access to mwm hints, and both feh and sxiv work just fine. Wherever the problem was, I squashed it.
In other words, the problem appears to lie in either lightdm or i3.