Add dynamic width to treecells

[Colbix]

+Added dynamic width to tree cell preferred size ~Consolidated location of menu class related items for consistency

[kaikramer]

Hm, this commit seems to reduce the space between the items.

Before:

Now:

I think there is even a bit cut off of the icons.

Could you please take a look into it?

[Colbix]

Good observation. I added a height padding variable which now looks similar to the before picture.