There are definitely some rendering problems in KoolGrid - specifically the rightmost column not finishing properly, but appearing to be far too wide.
It's ugly, but I can live with it - the problem comes when using the insert form in a detail table. The confirm and cancel buttons may appear momentarily at best but then just disappear. Because the right-most column "goes on forever", the buttons are always out of sight, so the form can't be submitted or cancelled.
This is a complete show-stopper which means I can't deploy to my client until it is fixed. Tried it with Chrome and Firefox - same problem. Won't allow IE on my systems, so haven't tested on that.
Any ideas anyone?

I've been using the Koolgrid for over 8 years and haven't had a size issue with it.
I can set the width, height, and customize all of the forms in it pretty well.
I haven't used an insert form inside of a details table though, so I'd like to see the issue.
Would you paste an image to show us what that looks like? It may help us with the problem for ourselves as well.

Master table insert form works as expected (note that the right-most column does not terminate correctly):
Detail table works as expected:
Click Add New Record and sometimes the confirm button can just be seen:
Touch the horizontal scroll bar the slightest amount and it disappears and cannot be found:

Did you specify how many pixels wide the detail grid should be?
If you did that, does the sum of the columns widths equal that grid width?

I tried defining width as a percentage as per examples but didn't know I could do it in px as well - will give that a try, thanks.

That's fixed it!
Many thanks - only been using Kool for a week or so, so still getting to grips with things.

While I think of it, I have one further query.
You can see I have "buildings" in the master table, with the detail table containing a building's "elements".
When I open the insert form I need the element's building id field to be set to point to the relevant building back in the master table - how do I do that?
Many thanks.

I would use the custom insert templates because I like full control of my html elements.
I used to use the built in insert and edit templates, but after I started using the custom insert templates, I really got spoiled by them.
If you need some samples, the guys at KoolPHP have them, but I added some to the code samples page as well to help others.
I'll place a link in here for you in a separate thread and a sample insert form I built with the Koolgrid.
As far as your detail table, I believe it should be selected already in your select statement.
I'm not sure since I can't debug it. Is it visible online?

Insert edit template samples.
https://www.koolphp.net/forum/threads/95.1/using-the-insert-and-edit-template.html

The system is subject to non-disclosure, so I shouldn't even be posting the screen grabs :-)

That looks like the way to go, just a matter of tackling the learning curve - many thanks.

Understandable. Sometimes when I have hard to tackle issues, I can submit a private ticket to the KoolPHP team and they usually do a good job of solving problems.
Usually bug related problems though.
Good luck and keep at it :)