ComboBox width?

I can set the width of a ComboBox field itself but how do I set the width of the drop down list? The problem is that the entries in my list are of varying width so the ComboBox is sizing the drop down list to the width of the widest entry. This causes the list to jump around and is quite annoying. What can I do? I want to set a fixed width for the list.

As far as I know, there is no official way to do this. You could try the following CSS, seems to work fine in a (simple) test case:

.v-filterselect-suggestpopup {
   overflow: hidden !important;
   width: 200px;

.v-filterselect-suggestmenu {
   width: 100% !important;

In Vaadin8 this would be done with setPopupWidth(null)