don't remove blank rows/cols more than once

Change-Id: I7b46ac1f9fcca5a3ae9dbb6b6c4f92917f522295

vcl/source/window/layout.cxx

@@ -543,11 +543,14 @@ VclGrid::array_type VclGrid::assembleGrid() const
         }
     }
 
-    //reduce the spans of elements that span empty rows or columns
+    //reduce the spans of elements that span empty columns
     for (sal_Int32 x = 0; x < nMaxX; ++x)
     {
+        std::set<ExtendedGridEntry*> candidates;
         for (sal_Int32 y = 0; y < nMaxY; ++y)
         {
+            if (aNonEmptyCols[x])
+                continue;
             ExtendedGridEntry &rSpan = A[x][y];
             //cell x/y is spanned by the widget at cell rSpan.x/rSpan.y,
             //just points back to itself if there's no cell spanning
@@ -558,10 +561,41 @@ VclGrid::array_type VclGrid::assembleGrid() const
                 continue;
             }
             ExtendedGridEntry &rEntry = A[rSpan.x][rSpan.y];
-            if (aNonEmptyCols[x] == false)
-                --rEntry.nSpanWidth;
-            if (aNonEmptyRows[y] == false)
-                --rEntry.nSpanHeight;
+            candidates.insert(&rEntry);
+        }
+        for (std::set<ExtendedGridEntry*>::iterator aI = candidates.begin(), aEnd = candidates.end();
+            aI != aEnd; ++aI)
+        {
+            ExtendedGridEntry *pEntry = *aI;
+            --pEntry->nSpanWidth;
+        }
+    }
+
+    //reduce the spans of elements that span empty rows
+    for (sal_Int32 y = 0; y < nMaxY; ++y)
+    {
+        std::set<ExtendedGridEntry*> candidates;
+        for (sal_Int32 x = 0; x < nMaxX; ++x)
+        {
+            if (aNonEmptyRows[y])
+                continue;
+            ExtendedGridEntry &rSpan = A[x][y];
+            //cell x/y is spanned by the widget at cell rSpan.x/rSpan.y,
+            //just points back to itself if there's no cell spanning
+            if ((rSpan.x == -1) || (rSpan.y == -1))
+            {
+                //there is no entry for this cell, i.e. this is a cell
+                //with no widget in it, or spanned by any other widget
+                continue;
+            }
+            ExtendedGridEntry &rEntry = A[rSpan.x][rSpan.y];
+            candidates.insert(&rEntry);
+        }
+        for (std::set<ExtendedGridEntry*>::iterator aI = candidates.begin(), aEnd = candidates.end();
+            aI != aEnd; ++aI)
+        {
+            ExtendedGridEntry *pEntry = *aI;
+            --pEntry->nSpanHeight;
         }
     }
 
@@ -612,7 +646,7 @@ void VclGrid::calcMaxs(const array_type &A, std::vector<Value> &rWidths, std::ve
         {
             const GridEntry &rEntry = A[x][y];
             const Window *pChild = rEntry.pChild;
-            if (!pChild)
+            if (!pChild || !pChild->IsVisible())
                 continue;
 
             sal_Int32 nWidth = rEntry.nSpanWidth;
@@ -643,7 +677,7 @@ void VclGrid::calcMaxs(const array_type &A, std::vector<Value> &rWidths, std::ve
         {
             const GridEntry &rEntry = A[x][y];
             const Window *pChild = rEntry.pChild;
-            if (!pChild)
+            if (!pChild || !pChild->IsVisible())
                 continue;
 
             sal_Int32 nWidth = rEntry.nSpanWidth;