Bug 345141 - arrows on scrollbars do nothing. Patch by Adam Guthrie, r+sr=roc

layout/xul/base/src/nsScrollbarButtonFrame.cpp

@@ -95,13 +95,14 @@ nsScrollbarButtonFrame::HandleEvent(nsPresContext* aPresContext,
   // if we didn't handle the press ourselves, pass it on to the superclass
   if (!HandleButtonPress(aPresContext, aEvent, aEventStatus))
     return nsButtonBoxFrame::HandleEvent(aPresContext, aEvent, aEventStatus);
+  return NS_OK;
 }
 
 
 PRBool
 nsScrollbarButtonFrame::HandleButtonPress(nsPresContext* aPresContext, 
-                                    nsGUIEvent*     aEvent,
-                                    nsEventStatus*  aEventStatus)
+                                          nsGUIEvent*     aEvent,
+                                          nsEventStatus*  aEventStatus)
 {
   // Get the desired action for the scrollbar button.
   nsILookAndFeel::nsMetricID tmpAction;
@@ -177,7 +178,6 @@ nsScrollbarButtonFrame::HandleButtonPress(nsPresContext* aPresContext,
       // We were told to ignore this click, or someone assigned a non-standard
       // value to the button's action.
       return PR_FALSE;
-      break;
   }
   // set this attribute so we can style it later
   mContent->SetAttr(kNameSpaceID_None, nsXULAtoms::active, NS_LITERAL_STRING("true"), PR_TRUE);

widget/src/gtk2/nsLookAndFeel.cpp

@@ -332,6 +332,19 @@ NS_IMETHODIMP nsLookAndFeel::GetMetric(const nsMetricID aID, PRInt32 & aMetric)
 {
     nsresult res = NS_OK;
 
+    // Set these before they can get overrided in the nsXPLookAndFeel. 
+    switch (aID) {
+    case eMetric_ScrollButtonLeftMouseButtonAction:
+        aMetric = 0;
+        return NS_OK;
+    case eMetric_ScrollButtonMiddleMouseButtonAction:
+        aMetric = 1;
+        return NS_OK;
+    case eMetric_ScrollButtonRightMouseButtonAction:
+        aMetric = 2;
+        return NS_OK;
+    }
+
     res = nsXPLookAndFeel::GetMetric(aID, aMetric);
     if (NS_SUCCEEDED(res))
         return res;
@@ -492,15 +505,6 @@ NS_IMETHODIMP nsLookAndFeel::GetMetric(const nsMetricID aID, PRInt32 & aMetric)
     case eMetric_ScrollSliderStyle:
         aMetric = eMetric_ScrollThumbStyleProportional;
         break;
-    case eMetric_ScrollButtonLeftMouseButtonAction:
-        aMetric = 0;
-        break;
-    case eMetric_ScrollButtonMiddleMouseButtonAction:
-        aMetric = 1;
-        break;
-    case eMetric_ScrollButtonRightMouseButtonAction:
-        aMetric = 2;
-        break;
     case eMetric_TreeOpenDelay:
         aMetric = 1000;
         break;

widget/src/xpwidgets/nsXPLookAndFeel.cpp

@@ -106,12 +106,6 @@ nsLookAndFeelIntPref nsXPLookAndFeel::sIntPrefs[] =
     eMetric_TreeScrollLinesMax, PR_FALSE, nsLookAndFeelTypeInt, 0 },
   { "accessibility.tabfocus",
     eMetric_TabFocusModel, PR_FALSE, nsLookAndFeelTypeInt, 0 },
-  { "ui.scrollbarButtonLeftMouseButtonAction",
-    eMetric_ScrollButtonLeftMouseButtonAction, PR_FALSE, nsLookAndFeelTypeInt, 0 },
-  { "ui.scrollbarButtonMiddleMouseButtonAction",
-    eMetric_ScrollButtonMiddleMouseButtonAction, PR_FALSE, nsLookAndFeelTypeInt, 3 },
-  { "ui.scrollbarButtonRightMouseButtonAction",
-    eMetric_ScrollButtonRightMouseButtonAction, PR_FALSE, nsLookAndFeelTypeInt, 3 },
   { "ui.alertNotificationOrigin",
     eMetric_AlertNotificationOrigin, PR_FALSE, nsLookAndFeelTypeInt, 0 },
 };
@@ -551,6 +545,20 @@ nsXPLookAndFeel::GetMetric(const nsMetricID aID, PRInt32& aMetric)
   if (!sInitialized)
     Init();
 
+  // Set the default values for these prefs. but allow different platforms
+  // to override them in their nsLookAndFeel if desired.
+  switch (aID) {
+    case eMetric_ScrollButtonLeftMouseButtonAction:
+      aMetric = 0;
+      return NS_OK;
+    case eMetric_ScrollButtonMiddleMouseButtonAction:
+      aMetric = 3;
+      return NS_OK;
+    case eMetric_ScrollButtonRightMouseButtonAction:
+      aMetric = 3;
+      return NS_OK;
+  }
+
   for (unsigned int i = 0; i < ((sizeof (sIntPrefs) / sizeof (*sIntPrefs))); ++i)
     if (sIntPrefs[i].isSet && (sIntPrefs[i].id == aID))
     {