I have two UP2718Q's side by side (both connected to the main machine, and the secondary one to other machines too) and although a desktop application like DDM seems like a nice bonus, the implementation is so shoddy that it has turned into disappointment. Playing around with it I found the following glaring issues :
1) Always getting the 'quick' DDM first is nothing but annoying when you (always) want the full DDM. Why not pop up the full one via the desktop background context menu, and the quick one via the taskbar ?
2) For such a simple application it sure takes a long time to start.
3) When switching input, the application window disappears without a trace, but is apparently still 'there', since restarting the application takes two clicks (and then another one, see point 1).
4) I cannot revert to 'None' for the shortcut keys. Once set to some key, DDM refuses to forget. Why not have an explicit 'save' for this as for the input port/name/etc. choices ?
5) Why not have an option to switch USB upstream without associating them with a particular video input ? I have two different machines showing on one monitor each, and want to switch keyboard/mouse between them, without switching video.
6) Why does the 'toggle' hotkey switch between two inputs only, when there are four ?
No comment on your #1, #5 and #6, which speak to Dell UI design decisions, but for the others:
#2 - DDC/CI is an I2C interface, which is inherently slow, and DDM doesn't "own" the monitors so it has to always sync with the OSD. If you think its slow with 2 x UP2718Q, you definitely wouldn't like using with a wall of 16 x P4317Qs.
#3 - when you switch the active input, the UI closes since the monitor should now be under control of the source you just switched to
#4 - to change a hotkey to "None" just hit the backspace key, same as the Windows shortcut property sheet
Thanks. That was enlightening.
#2 : Fair enough. I suppose at 100 kHz (or so), an I2C exchange with lots of superfluous data could become embarrassingly slow. I rather got the feeling it's simply bad implementation (and I'm not yet convinced that I'm wrong).
#3 : I'm not sure the control channel would need to move, along with the video. That doesn't make a whole lot of sense. EDIT (to clarify) : the other monitor's video (i.e. if I switch monitor B's input via monitor A's DDC/CI).
#4 : But it doesn't seem to save that. If I re-enter the DM, the old shortcut key is back. 'None' does not stick.