AppleScript - Changing Width of Dialog Box and Adding Text
Regarding "Changing Width of Dialog Box", I know of no method to decrease the width of a dialog box.


  How would one increase the width of the display dialog


One unsophisticated method to increase the width of a dialog does exist.

A dialog will automatically widen to accommodate the full width of (so as to not truncate) a button title. Consequently, you can add space characters to the button text (spaced out evenly on both ends for a symmetrical appearance) to increase the overall dialog width.

Using your sample dialog:





It looks funny to have such a broad button, but this is better than nothing, I suppose.

Using this method, you can make an AppleScript dialog as wide as your screen.

I'd prefer that this trick worked with the dialog title instead. But, if a dialog title exceeds the length of the dialog, the dialog title will simply be cut off, and an ellipsis will be appended.