Time: properly center the window.

* The previous code was broken, and did not take the actual window
  size into account; it's now using BWindow::MoveOnScreen().
* Also, make the width of the time zone list relative to the font size.

src/preferences/time/TimeWindow.cpp

@@ -149,18 +149,8 @@ TTimeWindow::_InitWindow()
 void
 TTimeWindow::_AlignWindow()
 {
-	BPoint pt = TimeSettings().LeftTop();
-	MoveTo(pt);
-
-	BRect frame = Frame();
-	BRect screen = BScreen().Frame();
-	if (!frame.Intersects(screen.InsetByCopy(50.0, 50.0))) {
-		BRect bounds(Bounds());
-		BPoint leftTop((screen.Width() - bounds.Width()) / 2.0,
-			(screen.Height() - bounds.Height()) / 2.0);
-
-		MoveTo(leftTop);
-	}
+	MoveTo(TimeSettings().LeftTop());
+	MoveOnScreen();
 }
 
 

src/preferences/time/ZoneView.cpp

@@ -213,7 +213,8 @@ TimeZoneView::_InitView()
 	_BuildZoneMenu();
 	BScrollView* scrollList = new BScrollView("scrollList", fZoneList,
 		B_FRAME_EVENTS | B_WILL_DRAW, false, true);
-	scrollList->SetExplicitMinSize(BSize(200, 0));
+	scrollList->SetExplicitMinSize(
+		BSize(200 * be_plain_font->Size() / 12.0f, 0));
 
 	fCurrent = new TTZDisplay("currentTime", B_TRANSLATE("Current time:"));
 	fPreview = new TTZDisplay("previewTime", B_TRANSLATE("Preview time:"));