--- a/layout/generic/nsBlockFrame.cpp
+++ b/layout/generic/nsBlockFrame.cpp
@@ -1339,20 +1339,18 @@ nsBlockFrame::ComputeFinalSize(const nsH
         // Truncate bottom margin if it doesn't fit to our available height.
         autoHeight = PR_MIN(autoHeight + aState.mPrevBottomMargin.get(), aState.mReflowState.availableHeight);
       }
     }
 
     if (aState.GetFlag(BRS_SPACE_MGR)) {
       // Include the space manager's state to properly account for the
       // bottom margin of any floated elements; e.g., inside a table cell.
-      nscoord ymost;
-      if (aReflowState.mSpaceManager->YMost(ymost) &&
-          autoHeight < ymost)
-        autoHeight = ymost;
+      nscoord floatHeight = aReflowState.mSpaceManager->ClearFloats(nscoord_MIN, NS_STYLE_CLEAR_LEFT_AND_RIGHT);
+      autoHeight = PR_MAX(autoHeight, floatHeight);
     }
 
     // Apply min/max values
     autoHeight -= borderPadding.top;
     nscoord oldAutoHeight = autoHeight;
     aReflowState.ApplyMinMaxConstraints(nsnull, &autoHeight);
     if (autoHeight != oldAutoHeight) {
       // Our min-height or max-height made our height change.  Don't carry out

--- a/layout/generic/nsSpaceManager.cpp
+++ b/layout/generic/nsSpaceManager.cpp
@@ -843,37 +843,31 @@ nsSpaceManager::InsertBandRect(BandRect*
     }
   }
 }
 
 nsresult
 nsSpaceManager::AddRectRegion(nsIFrame* aFrame, const nsRect& aUnavailableSpace)
 {
   NS_PRECONDITION(nsnull != aFrame, "null frame");
-
-#ifdef DEBUG
-  // See if there is already a region associated with aFrame
-  NS_ASSERTION(!GetFrameInfoFor(aFrame),
-               "aFrame is already associated with a region");
-#endif
   
   // Convert the frame to world coordinates
   nsRect  rect(aUnavailableSpace.x + mX, aUnavailableSpace.y + mY,
                aUnavailableSpace.width, aUnavailableSpace.height);
 
   if (rect.y > mLowestTop)
     mLowestTop = rect.y;
 
   // Create a frame info structure
   FrameInfo* frameInfo = CreateFrameInfo(aFrame, rect);
   if (nsnull == frameInfo) {
     return NS_ERROR_OUT_OF_MEMORY;
   }
 
-  if (aUnavailableSpace.height <= 0)
+  if (aUnavailableSpace.IsEmpty())
     return NS_OK;
 
   // Allocate a band rect
   BandRect* bandRect = new BandRect(rect.x, rect.y, rect.XMost(), rect.YMost(), aFrame);
   if (nsnull == bandRect) {
     return NS_ERROR_OUT_OF_MEMORY;
   }
 
@@ -914,17 +908,17 @@ nsSpaceManager::RemoveRegion(nsIFrame* a
   // Get the frame info associated with aFrame
   FrameInfo*  frameInfo = GetFrameInfoFor(aFrame);
 
   if (nsnull == frameInfo) {
     NS_WARNING("no region associated with aFrame");
     return NS_ERROR_INVALID_ARG;
   }
 
-  if (frameInfo->mRect.height > 0) {
+  if (!frameInfo->mRect.IsEmpty()) {
     NS_ASSERTION(!mBandList.IsEmpty(), "no bands");
     BandRect* band = mBandList.Head();
     BandRect* prevBand = nsnull;
     PRBool    prevFoundMatchingRect = PR_FALSE;
 
     // Iterate each band looking for rects tagged with aFrame
     while (nsnull != band) {
       BandRect* rect = band;