He's not missing your point at all.
The source of your problem is that you're wanting the height of X apples to be the same as the height of Y oranges. The row-height spacing of a list control using the 'check' option is fatter than the listbox without checkboxes, because it's accommodating the presence of the checkbox.
The /help can often be so brief that the text makes sense only after you understand what the $identifier or /command does. Sometimes I've had to glean clues from
versions.txt. However it does say that x y w h are the size of the control - which isn't necessarily the same as the size of the visual area of the control.
By default, the list control's window is a size that's rounded down to be the largest size that fits entire rows in the visual area. When using the 'size' option, that overrides the default and makes it create the window as large as possible for the 'h' you used to define the control.
So the list control is doing what you told it to do, even though you didn't realize you were telling it to do that - not what you want it to do. Depending on the 'h' value of the control, if 'size' changes the height of the window, you'll notice that it causes the window to contain a fraction of another row instead of showing only complete rows.
Depending on which 'h' you use to define your window, it's possible that some 'h' values could result in a checkbox window being taller while other 'h' values make the checkbox window shorter.
He tried to tell you that the dialog controls were very simple, and don't contain all features. For example, you can't override the centering of a button's text without padding $str($chr(160),N) to the right or left of your text label.
I'm not sure what you mean by being able to change the spacing of items in a text control. You can wrap the text, but it always has the same default spacing between wrapped rows.
The purpose of "option dbu" is so you can make something that looks the same for someone having an 800x600 monitor as for someone on a 1920x1080. It shows the same font, which seems to be sized according to someone's screen resolution, and it doesn't let you change that. It divides by $dbuw and $dbuh which supposedly can be different, but I've never found anyone who had differing values. I posted a request to even find out which font gets used, and got no answers.
https://forums.mirc.com/ubbthreads.php/topics/260772/Font_Name/Size_in_Dialog_text_
