make VerticalScroll::move_top for PageUp nicer

Author: xlai89

src/components/utils/scroll_vertical.rs

@@ -36,16 +36,11 @@ impl VerticalScroll {
 			ScrollType::Down => old.saturating_add(1),
 			ScrollType::Up => old.saturating_sub(1),
 			ScrollType::PageDown => old
-				.saturating_add(self.visual_height.get())
-				.saturating_sub(1),
-			ScrollType::PageUp => {
-				if old < self.visual_height.get() {
-					0
-				} else {
-					old.saturating_sub(self.visual_height.get())
-						.saturating_add(1)
-				}
-			}
+				.saturating_sub(1)
+				.saturating_add(self.visual_height.get()),
+			ScrollType::PageUp => old
+				.saturating_add(1)
+				.saturating_sub(self.visual_height.get()),
 			ScrollType::Home => 0,
 			ScrollType::End => max,
 		};