fix for #77506. r=varada, sr=bienvenu

prevent the bad state where we are supressing message display, but the message pane
is not hidden.

mailnews/base/resources/content/commandglue.js

@@ -583,11 +583,7 @@ function CreateDBView(msgFolder, viewType, viewFlags, sortType, sortOrder)
 
   // based on the collapsed state of the thread pane/message pane splitter,
   // supress message display if appropriate.
-  var collapsed = IsThreadAndMessagePaneSplitterCollapsed();
-  if (collapsed)
-    gDBView.supressMsgDisplay = true;
-  else
-    gDBView.supressMsgDisplay = false;
+  gDBView.supressMsgDisplay = IsThreadAndMessagePaneSplitterCollapsed();
 
   UpdateSortIndicators(gCurSortType, sortOrder);
   PersistViewAttributesOnFolder();
@@ -680,30 +676,22 @@ function GetSelectedFolderResource()
 	return folderResource;
 }
 
-//Called when the splitter in between the thread and message panes is clicked.
-function OnClickThreadAndMessagePaneSplitter()
-{
-  var collapsed = IsThreadAndMessagePaneSplitterCollapsed();
-  // collapsed is the previous state, so we must be expanding
-  // the splitter if collapsed is true
-  if (gDBView)
+function OnMouseUpThreadAndMessagePaneSplitter()
   {
-    if (!collapsed)
-      gDBView.supressMsgDisplay = true;
-    else
-      gDBView.supressMsgDisplay = false;
+  if (gDBView) {
+    // the collapsed state is the state after we released the mouse 
+    // so we take it as it is
+    gDBView.supressMsgDisplay = IsThreadAndMessagePaneSplitterCollapsed();
+  }
   }
 
-/*
-  dump("We are in OnClickThreadAndMessagePaneSplitter()\n");
-  var collapsed = IsThreadAndMessagePaneSplitterCollapsed();
-  //collapsed is the previous state so we know we are opening.
-  if(collapsed)
+function OnClickThreadAndMessagePaneSplitterGrippy()
   {
-    LoadSelectionIntoMessagePane();
-    setTimeout("ScrollToMessage(new,true,true);",0);
+  if (gDBView) {
+    // the collapsed state is the state when we clicked on the grippy
+    // not when afterwards, so we need to reverse this value
+    gDBView.supressMsgDisplay = !IsThreadAndMessagePaneSplitterCollapsed();
    }
-*/
 }
 
 function FolderPaneSelectionChange()

mailnews/base/resources/content/mail3PaneWindowVertLayout.xul

@@ -152,8 +152,9 @@ Rights Reserved.
       </box>
       <!-- if you change this id, please change GetThreadAndMessagePaneSplitter() and MsgToggleMessagePane() -->
       <splitter id="threadpane-splitter" collapse="after" persist="state"
+	 onmouseup="OnMouseUpThreadAndMessagePaneSplitter()"
          orient="vertical" autostretch="never">
-        <grippy onclick="OnClickThreadAndMessagePaneSplitter()" />
+        <grippy onclick="OnClickThreadAndMessagePaneSplitterGrippy()"/>
       </splitter>
       <!-- msg header view -->
       <box id="messagepanebox" orient="vertical" flex="4" persist="collapsed height" class="window-focusborder" focusring="false">

mailnews/base/resources/content/messenger.xul

@@ -154,8 +154,9 @@ Rights Reserved.
 
       <!-- if you change this id, please change GetThreadAndMessagePaneSplitter() and MsgToggleMessagePane() -->
       <splitter collapse="after" persist="state" 
+		onmouseup="OnMouseUpThreadAndMessagePaneSplitter()"
                 id="threadpane-splitter" orient="vertical" autostretch="never">
-        <grippy onclick="OnClickThreadAndMessagePaneSplitter()"/>
+        <grippy onclick="OnClickThreadAndMessagePaneSplitterGrippy()"/>
       </splitter>
       
       <box id="messagepanebox" align="vertical" flex="3" persist="collapsed height" class="window-focusborder" focusring="false" onclick="contentAreaClick(event);" ondraggesture="nsDragAndDrop.startDrag(event, contentAreaDNDObserver);">

mailnews/base/resources/content/msgMail3PaneWindow.js

@@ -642,16 +642,16 @@ function GetTotalCountElement()
 	gTotalCount = totalCount;
 	return totalCount;
 }
+
 function IsThreadAndMessagePaneSplitterCollapsed()
 {
-	var splitter = GetThreadAndMessagePaneSplitter();
-	if(splitter)
-	{
-		var state  = splitter.getAttribute('state');
-		return (state == "collapsed");
+  var messagePane = GetMessagePane();
+  try {
+    return (messagePane.getAttribute("collapsed") == "true");
 	}
-	else
+  catch (ex) {
 		return false;
+  }
 }
 
 function FindMessenger()