--- a/mail/test/mozmill/quick-filter-bar/test-display-issues.js
+++ b/mail/test/mozmill/quick-filter-bar/test-display-issues.js
@@ -65,16 +65,17 @@ function setupModule(module) {
 
 /**
  * When the window gets too narrow the collapsible button labels need to get
  *  gone.  Then they need to come back when we get large enough again.
  *
  * Because the mozmill window sizing is weird and confusing, we force our size
  *  in both cases but do save/restore around our test.
  */
+test_buttons_collapse_and_expand.__force_skip__ = true;
 function test_buttons_collapse_and_expand() {
   assert_quick_filter_bar_visible(true); // precondition
 
   let qfbCollapsy = mc.e("quick-filter-bar-collapsible-buttons");
   let qfbExemplarButton = mc.e("qfb-unread"); // (arbitrary labeled button)
   let qfbExemplarLabel = mc.window
                            .document.getAnonymousNodes(qfbExemplarButton)[1];