Prevent corrupted measurements due to vanishing/appearing scrollbar

Issue #1787
codemirror · Sep 6, 2013 · c8c7fc1 · c8c7fc1
1 parent 30a9ee5
commit c8c7fc1
Showing 1 changed file with 5 additions and 3 deletions.
diff --git a/lib/codemirror.js b/lib/codemirror.js
@@ -355,6 +355,7 @@ window.CodeMirror = (function() {
 
     if (mac_geLion && scrollbarWidth(d.measure) === 0)
       d.scrollbarV.style.minWidth = d.scrollbarH.style.minHeight = mac_geMountainLion ? "18px" : "12px";
+    return needsV;
   }
 
   function visibleLines(display, doc, viewPort) {
@@ -410,11 +411,13 @@ window.CodeMirror = (function() {
     var oldFrom = cm.display.showingFrom, oldTo = cm.display.showingTo, updated;
     var visible = visibleLines(cm.display, cm.doc, viewPort);
     for (;;) {
+      var hadVScroll = cm.display.scroller.scrollHeight > cm.display.scroller.clientHeight + 1;
       if (!updateDisplayInner(cm, changes, visible, forced)) break;
-      forced = false;
       updated = true;
+      changes = [];
       updateSelection(cm);
-      updateScrollbars(cm);
+      if (updateScrollbars(cm) != hadVScroll) continue;
+      forced = false;
 
       // Clip forced viewport to actual scrollable area
       if (viewPort)
@@ -423,7 +426,6 @@ window.CodeMirror = (function() {
       visible = visibleLines(cm.display, cm.doc, viewPort);
       if (visible.from >= cm.display.showingFrom && visible.to <= cm.display.showingTo)
         break;
-      changes = [];
     }
 
     if (updated) {