Did you guys even beta test this?

Can you grab the bottom of the window with the mouse and resize the dialog?

No, the window is not resizeable.

Clarification: I the mouse icon indicates that the window should be resizeable, but clicking and dragging does nothing.  (When mousing over the bottom of the dialog, it shows the up/down arrows.)

What resolution are you currently running at? 

Minimum resolution for CircuitStudio is currently 1280x1024 at 100% scaling

So, if you are at 1024 or around there, and scaling is set higher than 100% within Windows, some dialogs can get a chop effect like you are seeing here.  If you are at or below 1024, and also at a higher scaling it could end up looking like your screenshot.

If your maximum vertical resolution cannot reach 1024, you will have to run at 100% scaling for CircuitStudio, and some dialogs might still be difficult to see.  But in these cases, please let us know the resolution and scaling you are running at and if it is a dialog we can improve, we can submit a ticket for review.

This table is pretty handy for mapping scaling to resolution for CircuitStudio, I hope it helps, but keep in mind that even at Maximum scaling for a resolution, on widescreen ratios I have still seen some minor dialog chopping so although it might say 250%, if you see a dialog chopped, try dropping to 200% and see if it improves.

Scaling is changed within Windows 10 by accessing your Display Settings in the Scale and Layout section.

I can certainly make the dialog larger (there is a minimum size so cannot shrink too much, certainly not to the extent you see). Can you resize using the keyboard? With the dialog active use ALT+SPACE to activate the system menu and select S (Size) then try using the down arrow key to expand.

In my installation I indeed get the mouse indications that the window can be resized but the window is a fixed size and the mouse handles have no effect.  Maybe the OP should try different screen resolutions or even an external monitor.  Here is what the window should look like.

I tried this, and the window can't be resized by any method so far described.  I tried dragging the bottom edge down as well as using the Alt+Space menu to try invoking Window's resize command directly.  Even using the keyboard exclusively like Peter said does not accomplish any change.

As I mentioned before, this is stock Windows 10 on a Surface Book 2.  I haven't changed any settings, but my current display settings are within the ranges your table specifies.  I also tried a second display (2560x1440 @ 100% scale) with no change.

One more thing you can try to resize the dialog, this is at your own risk as it edits the registry. Run regedit and go to Computer\HKEY_CURRENT_USER\Software\Altium\CircuitStudio {guid}\DesignExplorer\Forms\TGridEditorForm, there you will find the dialog size and position values that you can try changing. You can change with the program running and dialog closed, next time you invoke the dialog it should read the registry values.

Hmm, should definitely look close to how I see mine, your settings are not too different than how I run.

If you are not comfortable changing the registry, but are comfortable having a look, can you please go to the Registry key Peter referenced above and take a screenshot of the values?

HKEY_CURRENT_USER\Software\Altium\CircuitStudio {guid}\DesignExplorer\Forms\TGridEditorForm

As a reference, here is how mine look for this particular form.

I am curious if your values are somehow different, maybe an issue during install or something.  At minimum we can get a ticket submitted to make this dialog resizable, but my troubleshooting brain is curious as to the cause of this so hopefully we can get to the root of it