diff -r b72c6db6890b -r 5dc02b23752f src/gui/painting/qdatabuffer_p.h
--- a/src/gui/painting/qdatabuffer_p.h	Wed Jun 23 19:07:03 2010 +0300
+++ b/src/gui/painting/qdatabuffer_p.h	Tue Jul 06 15:10:48 2010 +0300
@@ -60,16 +60,20 @@
 template <typename Type> class QDataBuffer
 {
 public:
-    QDataBuffer(int res = 64)
+    QDataBuffer(int res)
     {
         capacity = res;
-        buffer = (Type*) qMalloc(capacity * sizeof(Type));
+        if (res)
+            buffer = (Type*) qMalloc(capacity * sizeof(Type));
+        else
+            buffer = 0;
         siz = 0;
     }
 
     ~QDataBuffer()
     {
-        qFree(buffer);
+        if (buffer)
+            qFree(buffer);
     }
 
     inline void reset() { siz = 0; }
@@ -81,7 +85,9 @@
 
     inline Type &at(int i) { Q_ASSERT(i >= 0 && i < siz); return buffer[i]; }
     inline const Type &at(int i) const { Q_ASSERT(i >= 0 && i < siz); return buffer[i]; }
+    inline Type &last() { Q_ASSERT(!isEmpty()); return buffer[siz-1]; }
     inline const Type &last() const { Q_ASSERT(!isEmpty()); return buffer[siz-1]; }
+    inline Type &first() { Q_ASSERT(!isEmpty()); return buffer[0]; }
     inline const Type &first() const { Q_ASSERT(!isEmpty()); return buffer[0]; }
 
     inline void add(const Type &t) {
@@ -90,6 +96,11 @@
         ++siz;
     }
 
+    inline void pop_back() {
+        Q_ASSERT(siz > 0);
+        --siz;
+    }
+
     inline void resize(int size) {
         reserve(size);
         siz = size;
@@ -97,6 +108,8 @@
 
     inline void reserve(int size) {
         if (size > capacity) {
+            if (capacity == 0)
+                capacity = 1;
             while (capacity < size)
                 capacity *= 2;
             buffer = (Type*) qRealloc(buffer, capacity * sizeof(Type));
@@ -105,7 +118,12 @@
 
     inline void shrink(int size) {
         capacity = size;
-        buffer = (Type*) qRealloc(buffer, capacity * sizeof(Type));
+        if (size)
+            buffer = (Type*) qRealloc(buffer, capacity * sizeof(Type));
+        else {
+            qFree(buffer);
+            buffer = 0;
+        }
     }
 
     inline void swap(QDataBuffer<Type> &other) {