I recently updated my shotcut to 18.08.01 and i am running it on a HP Laptop running Windows 10 Home version 1803 build 17134.165.
For some reason, when i make Shotcut fullscreen it tends to go beyond the borders of the screen, so that part of the timeline cannot be seen and used properly - I can’t scroll sideways, because the bar is under my screen. I then have to make Shotcut Windowed and then fullscreen again.
Was it the same with your prededent Shotcut version. Number of prevous version?
There is no fullscreen function in Shotcut for Windows. Do you mean the Windows maximize button?
I do not reproduce the problem if I maximize close and reopen. Shotcut is just using a couple of high level library function calls to save and restore window state. So, not sure I can fix that directly, but perhaps a future library upgrade will.
Yes, it is the maximize 
It happens from time to time with no pattern - when i save (mostly), when I add something to the timeline etc. etc. Maybe my laptop is week? Idk 
But it does go under the processline in windows - I am not able to see if it continues further than that And it did happen with previous versions as well. I don’t think I startet using shotcut before version 17.xx.xx
Yes it was
In your Display Settings (Windows 10):
Is “Scale & Layout” set at 100%?
Is “Resolution” set to what’s Recommended?
If you go to “Advanced display settings” it will show you what your actual physical display resolution is.
I was able to stretch the window a bit beyond what was usable, but every time I hit the maximize button, I was able to see everything. Have you tried restoring the default layout?
View -> Layout -> Restore Default Layout
I can’t duplicate the issue. I have 24" and 27" monitors, and both worked the same.
Desktop PC, Windows 10 Home 1803 (OS Build 17134.165)
Shotcut 18.08.01
I haven’t looked into these settings, but I will try it and come with a response as when I have news
Since nobody else has experienced it, it may be my computer that is the problem and perhaps not the software