Here is an updated patch which solves the problem of more large query which deals fine with zoom factor as well .
FYI: During testing it was found that the previous patch was only working for mid sized query and not more large complex query due to zoom factor issue.
Attached is the patch to fix the rightmost & bottom tooltip crop issues in the explain query plan.
FYI : While explaining a large query if we hover the rightmost or bottom icon the tooltip is cropped & partially visible, which is fixed in this patch.