Crash on resizing alignment in MSAEditor with tree view

Steps to reproduce:

1) Open "samples/CLUSTALW/COI.aln".
2) Click the "Build Tree" button on the toolbar.
3) Choose "Display tree with alignment editor".
4) Build.
Expected: the tree appears synchronized with the MSA Editor. Clustering blue line is shown.
5) Click the "Layout" button on the Tree View toolbar and choose the circular or unrooted layout.
6) Press "Zoom in" or "Zoom out" in alignment toolbar