I often use K/run/ rotate mouse wheel to find recent programs started from run dialog. Why not include it in the menu itself?
Or use it for recently started programs from the K-menu itself (for example when you launch Editors/Kwrite)
Saves a lot of space, and does not change K menu appearance like XP start menu.
And it does not increase height of the menu like recent apps in k menu.
Combobox also could be used, instead of spinbox. Editable or not eitable.