Bug 201299. Make lazy scrollbars more selective to avoid XUL tree and listbox problems. r+sr=bzbarsky

git-svn-id: svn://10.0.0.236/trunk@140907 18797224-902f-48f8-a5cc-f745e15eee43

mozilla/content/shared/public/nsXULAtomList.h

@@ -175,6 +175,7 @@ XUL_ATOM(increment, "increment")
 XUL_ATOM(pageincrement, "pageincrement")
 XUL_ATOM(thumb, "thumb")
 XUL_ATOM(toggled, "toggled")
+XUL_ATOM(lazy, "lazy")
 XUL_ATOM(grippy, "grippy")
 XUL_ATOM(splitter, "splitter")
 XUL_ATOM(collapse, "collapse")

mozilla/layout/generic/nsGfxScrollFrame.cpp

@@ -419,6 +419,11 @@ nsGfxScrollFrame::CreateAnonymousContent(nsIPresContext* aPresContext,
     }
   }
 
+  // Add the "lazy" attribute if the content is non-XUL (and therefore
+  // we can be sure no mediator is involved). Style rules in xul.css
+  // make sure that "lazy" scrollbars are XBL-bound only when needed.
+  PRBool lazyScrollbar = !mContent->IsContentOfType(nsIContent::eXUL);
+
   // create horzontal scrollbar
   nsresult rv;
   nsCOMPtr<nsIElementFactory> elementFactory = 
@@ -444,6 +449,10 @@ nsGfxScrollFrame::CreateAnonymousContent(nsIPresContext* aPresContext,
   content->SetAttr(kNameSpaceID_None, nsXULAtoms::collapsed,
                    NS_LITERAL_STRING("true"), PR_FALSE);
 
+  if (lazyScrollbar)
+    content->SetAttr(kNameSpaceID_None, nsXULAtoms::lazy,
+                     NS_LITERAL_STRING("true"), PR_FALSE);
+
   aAnonymousChildren.AppendElement(content);
 
   // create vertical scrollbar
@@ -455,6 +464,10 @@ nsGfxScrollFrame::CreateAnonymousContent(nsIPresContext* aPresContext,
   content->SetAttr(kNameSpaceID_None, nsXULAtoms::collapsed,
                    NS_LITERAL_STRING("true"), PR_FALSE);
 
+  if (lazyScrollbar)
+    content->SetAttr(kNameSpaceID_None, nsXULAtoms::lazy,
+                     NS_LITERAL_STRING("true"), PR_FALSE);
+
   aAnonymousChildren.AppendElement(content);
 
       // XXX For GFX never have scrollbars

mozilla/layout/html/base/src/nsGfxScrollFrame.cpp

@@ -419,6 +419,11 @@ nsGfxScrollFrame::CreateAnonymousContent(nsIPresContext* aPresContext,
     }
   }
 
+  // Add the "lazy" attribute if the content is non-XUL (and therefore
+  // we can be sure no mediator is involved). Style rules in xul.css
+  // make sure that "lazy" scrollbars are XBL-bound only when needed.
+  PRBool lazyScrollbar = !mContent->IsContentOfType(nsIContent::eXUL);
+
   // create horzontal scrollbar
   nsresult rv;
   nsCOMPtr<nsIElementFactory> elementFactory = 
@@ -444,6 +449,10 @@ nsGfxScrollFrame::CreateAnonymousContent(nsIPresContext* aPresContext,
   content->SetAttr(kNameSpaceID_None, nsXULAtoms::collapsed,
                    NS_LITERAL_STRING("true"), PR_FALSE);
 
+  if (lazyScrollbar)
+    content->SetAttr(kNameSpaceID_None, nsXULAtoms::lazy,
+                     NS_LITERAL_STRING("true"), PR_FALSE);
+
   aAnonymousChildren.AppendElement(content);
 
   // create vertical scrollbar
@@ -455,6 +464,10 @@ nsGfxScrollFrame::CreateAnonymousContent(nsIPresContext* aPresContext,
   content->SetAttr(kNameSpaceID_None, nsXULAtoms::collapsed,
                    NS_LITERAL_STRING("true"), PR_FALSE);
 
+  if (lazyScrollbar)
+    content->SetAttr(kNameSpaceID_None, nsXULAtoms::lazy,
+                     NS_LITERAL_STRING("true"), PR_FALSE);
+
   aAnonymousChildren.AppendElement(content);
 
       // XXX For GFX never have scrollbars

mozilla/xpfe/global/resources/content/xul.css

@@ -723,8 +723,11 @@ scrollbar {
   direction: ltr;
 }
 
-scrollbar[collapsed="true"],
-scrollbar[moz-collapsed="true"] {
+/* Scrollbars which have been marked 'lazy' are unbound while
+   collapsed; this saves anonymous content creation for scrollbars
+   which are not visible */
+scrollbar[lazy="true"][collapsed="true"],
+scrollbar[lazy="true"][moz-collapsed="true"] {
   -moz-binding: none;
 }