Bug 575245 - Fix for fx window z-Level issue with windows taskbar set to auto-hide. r=neil, sr=jimm.

widget/src/windows/nsWindow.cpp

@@ -1974,34 +1974,46 @@ nsWindow::UpdateNonClientMargins(PRInt32 aSizeMode, PRBool aReflowWindow)
   else if (mNonClientMargins.top > 0)
     mNonClientOffset.top = mCaptionHeight - mNonClientMargins.top;
 
-   if (!mNonClientMargins.left)
+  if (!mNonClientMargins.left)
     mNonClientOffset.left = mHorResizeMargin;
-   else if (mNonClientMargins.left > 0)
+  else if (mNonClientMargins.left > 0)
     mNonClientOffset.left = mHorResizeMargin - mNonClientMargins.left;
  
-   if (!mNonClientMargins.right)
+  if (!mNonClientMargins.right)
     mNonClientOffset.right = mHorResizeMargin;
-   else if (mNonClientMargins.right > 0)
+  else if (mNonClientMargins.right > 0)
     mNonClientOffset.right = mHorResizeMargin - mNonClientMargins.right;
 
-   if (!mNonClientMargins.bottom)
+  if (!mNonClientMargins.bottom)
     mNonClientOffset.bottom = mVertResizeMargin;
-   else if (mNonClientMargins.bottom > 0)
+  else if (mNonClientMargins.bottom > 0)
     mNonClientOffset.bottom = mVertResizeMargin - mNonClientMargins.bottom;
 
-  NS_ASSERTION(mNonClientOffset.top >= 0, "non-client top margin is negative!");
-  NS_ASSERTION(mNonClientOffset.left >= 0, "non-client left margin is negative!");
-  NS_ASSERTION(mNonClientOffset.right >= 0, "non-client right margin is negative!");
-  NS_ASSERTION(mNonClientOffset.bottom >= 0, "non-client bottom margin is negative!");
-
-  if (mNonClientOffset.top < 0)
-    mNonClientOffset.top = 0;
-  if (mNonClientOffset.left < 0)
-    mNonClientOffset.left = 0;
-  if (mNonClientOffset.right < 0)
-    mNonClientOffset.right = 0;
-  if (mNonClientOffset.bottom < 0)
-    mNonClientOffset.bottom = 0;
+#ifndef WINCE
+  if (aSizeMode == nsSizeMode_Maximized) {
+    // Address an issue with auto-hide taskbars which fall behind the window.
+    // Ensure a 1 pixel margin at the bottom of the monitor so that unhiding
+    // the taskbar works properly.
+    MONITORINFO info = {sizeof(MONITORINFO)};
+    if (::GetMonitorInfo(::MonitorFromWindow(mWnd, MONITOR_DEFAULTTOPRIMARY),
+                         &info)) {
+      RECT r;
+      if (::GetWindowRect(mWnd, &r)) {
+        // Adjust window rect to account for non-client margins.
+        r.top += mVertResizeMargin - mNonClientOffset.top;
+        r.left += mHorResizeMargin - mNonClientOffset.left;
+        r.bottom -= mVertResizeMargin - mNonClientOffset.bottom;
+        r.right -= mHorResizeMargin - mNonClientOffset.right;
+        // Leave the 1 pixel margin if the window covers the monitor.
+        if (r.top <= info.rcMonitor.top &&
+            r.left <= info.rcMonitor.left && 
+            r.right >= info.rcMonitor.right &&
+            r.bottom >= info.rcMonitor.bottom)
+          mNonClientOffset.bottom -= r.bottom - info.rcMonitor.bottom + 1;
+      }
+    }
+  }
+#endif
 
   if (aReflowWindow) {
     // Force a reflow of content based on the new client
@@ -5942,6 +5954,17 @@ void nsWindow::OnWindowPosChanged(WINDOWPOS *wp, PRBool& result)
 #ifdef WINSTATE_DEBUG_OUTPUT
     printf("*** Resize window: %d x %d x %d x %d\n", wp->x, wp->y, newWidth, newHeight);
 #endif
+    
+    // If a maximized window is resized, recalculate the non-client margins and
+    // ensure a 1 pixel margin at screen bottom to allow taskbar unhiding to
+    // work properly.
+    if (mSizeMode == nsSizeMode_Maximized) {
+      if (UpdateNonClientMargins(nsSizeMode_Maximized, PR_TRUE)) {
+        // gecko resize event already sent by UpdateNonClientMargins.
+        result = PR_TRUE;
+        return;
+      }
+    }
 
     // Recalculate the width and height based on the client area for gecko events.
     if (::GetClientRect(mWnd, &r)) {