[RobbieZ]

This is controlled in editor.css using math and a stylevar

width:{vb:math {vb:raw vboptions.smcolumns} * ({vb:stylevar editor_smiliebox_smiliesize} + 5)};

It basically works out the bigger your smilie and the size of the tablecell it is positioned it will resize accordingly.

Most smilies are usually 16x16 px and leaves them alone, I use 24x24px on my board and this is subsequently reduced to 20px because of this stylevar.

editor_smiliebox_smiliesize

Try changing this!