I have most of my commonly used bookmarks set up in sub folders by topic
within my personal toolbar folder. This gives the effect of dropdown
menus, which is very handy.
In Mozilla 0.9.1 (and earlier), holding down the mouse button over one
of these sub folders on my toolbar popped up the menu, which stayed open
until the mouse button was released (with the action of opening the
bookmark the mouse was over).
In 0.9.2 if you hold the mouse button, mozilla tries to drag the toolbar
folder instead.
I can still access the items by using a windows style click and release
method rather than a click and hold, but if feels inconsistant to have
to use that method to access the toolbar items.