Port Bug #241187 --> [gtk2]combo box shows up unexpectly due to nsWindow::IsVisible() does not return the right value

git-svn-id: svn://10.0.0.236/branches/AVIARY_1_0_20040515_BRANCH@157760 18797224-902f-48f8-a5cc-f745e15eee43

mozilla/widget/src/gtk2/nsWindow.cpp

@@ -435,6 +435,11 @@ NS_IMETHODIMP
 nsWindow::IsVisible(PRBool & aState)
 {
     aState = mIsVisible;
+    if(mIsTopLevel && mShell && !GTK_WIDGET_MAPPED(mShell)) {
+        /* we do not change mIsVisible to PR_FALSE here so we don't bother to
+           to change it back to PR_TRUE when the mShell is mapped again. */
+        aState = PR_FALSE;
+    }
     return NS_OK;
 }