optimized piano roll and automation editor paint events

git-svn-id: https://lmms.svn.sf.net/svnroot/lmms/trunk/lmms@620 0778d3d1-df1d-0410-868b-ea421aaaa00d

data/themes/default/style.css

@@ -4,12 +4,20 @@ QMdiArea {
 	background-image: url(resources:background_artwork.png);
 }
 
+automationEditor {
+	background-color: rgb(0, 0, 0);
+}
+
 captionMenu::item:disabled {
 	color: white;
 	background-color: rgb(0, 0, 192);
 	text-align: center;
 }
 
+pianoRoll {
+	background-color: rgb(0, 0, 0);
+}
+
 trackOperationsWidget > QPushButton {
 	max-height: 26px;
 	max-width: 26px;