Ok, here we go!
1) Please change default
Port to
/dev/ttyACM0 (my mistake I haven't said that before

);
2) Why buttons are bold but not pressed? (this observation is related not only to
SteelDrive, all drivers have the same behaviour)
3) No reaction on
Focus In /
Focus Out buttons (it seems no commands are sent). Their LED should be grey when they are not pressed, yellow than pressed (because while the button is still pressed focuser should be moving, which is a on-going process). And another thing - after pressing Connect I can get
Focus In button pressed, which is strange;
4) Focus speed has a range between 350 and 1000;
5) What is
Focus Timer?
6) Relative position can be not only of positive value (and yeah, it doesn't work for any value -
Requested position out of bound. Focus minimum position is 0, even if
Absolute Position shows 0 and the value I set can't be negative);
7)
Absolute Position - doesn't work (missing # at the end of the command);
8 ) Temperature gathering frequency is too high in my opinion - user don't need such a frequency. You can lower it to 1-2 fps. If you disagree - give the possibility to choose it

;
9) If I get thermal probe out - I get error in the log (
Unknown error: focuser temperature value , but the temperature doesn't change in the interface). When I put the probe back temperature starts updating again. May be in case of no thermal probe it is a good idea to show user red LED?
10)
Sync Position is in mm, yes?
11) Please put a dot in the
Date (between month and year) in
Version 
12) Make please default T coefficient 0.100. And setting
Temperature Settings doesn't work (I see no command is sent for
Coefficient and for the
# of Samples again # missing);
13)
Temperature Compensate buttons (
Enable /
Disable) doesn't work - you are missing # at the end of the commands;
14)
Custom Settings - the same story with missing # at the end;
15)
Acceleration - no command for writing is sent;
16) There is no button for storing parameters permanently (check my list - there is such a command).
Sorry for such a long list - I worked for a year in QA department

In any case thanks for your efforts, it is so great to see work in progress!