Taskbar (vertical): Change heights of tasks possible? (mainly: smaller frame around icons)

The Taskbar is vertical. The option to use small icons is set.
But the taks still need more space than nessecary, is the height which every task takes up configurable? Mainly: The frame around the task and the icon, cutting four pixels above and below looks possible and give us a higher task density there. And remove or lower the gap between different tasks (or task groups).
The same could be useful for the horizontal bar too..
jou@gmx.net /