Improve scrollbar-mouse interaction (#667)

* fix scrollbar detection on high devicePixelRatio devices

* don't create a new element on pointerdown over a scrollbar

* Return scrollbars from renderScene and use it in isOverScrollBars

* remove unneeded setState

* show default cursor when hovering or dragging a scrollbar

* disable scrollbars when in multielement mode

Co-authored-by: David Luzar <luzar.david@gmail.com>

src/scene/types.ts

@@ -19,3 +19,18 @@ export interface Scene {
 }
 
 export type ExportType = "png" | "clipboard" | "backend" | "svg";
+
+export type ScrollBars = {
+  horizontal: {
+    x: number;
+    y: number;
+    width: number;
+    height: number;
+  } | null;
+  vertical: {
+    x: number;
+    y: number;
+    width: number;
+    height: number;
+  } | null;
+};