Incorrect size of node buttons in PhyTree view on window resize

To reproduce:
1. Open any tree
2. Notice node (circle) sizes
3. Resize the view: the whole window or the view only using the project view slider

Current result: node size changes proportionally to the view size
Expected behavior: node size is constant (like during zoom-in/out operation with a mouse-wheel).

Nodes are intractable elements and must always keep 'clickable' dimensions.