Created attachment 7953 Improved Layout The attached patch applies the standard 6/12/18 spacing to the Smart Bookmark plugin. It also rearranges the input to better balance the look & feel of the dialog.
Sean Davis referenced this bugreport in commit cd9002b5fff63264a06ca985e83fdfc6d2dda621 Preferences: Improve spacing and layout (bug #14675) https://git.xfce.org/panel-plugins/xfce4-smartbookmark-plugin/commit?id=cd9002b5fff63264a06ca985e83fdfc6d2dda621
Patch applied with the above commit.