add offset / scrolling + clipboard support

src/layout/painter.rs

@@ -131,7 +131,9 @@ impl<'a> PainterCtx<'a> {
             if active.region == region {
                 return;
             } else if active.region.size() == region.size() {
-                self.mov(id, region);
+                // TODO: epsilon?
+                let from = active.region;
+                self.mov(id, from, region);
                 return;
             }
             let active = self.remove(id).unwrap();
@@ -185,22 +187,21 @@ impl<'a> PainterCtx<'a> {
         self.active.insert(id, instance);
     }
 
-    fn mov(&mut self, id: Id, to: UiRegion) {
+    fn mov(&mut self, id: Id, from: UiRegion, to: UiRegion) {
         let active = self.active.get_mut(&id).unwrap();
         // children will not be changed, so this technically should not be needed
         // probably need unsafe
-        let from = active.region;
         for h in &active.primitives {
             let region = self.layers[h.layer].primitives.region_mut(h);
             *region = region.outside(&from).within(&to);
         }
-        active.region = to;
+        active.region = active.region.outside(&from).within(&to);
         for m in self.modules.iter_mut() {
             m.on_move(active);
         }
         let children = active.children.clone();
         for child in children {
-            self.mov(child, to);
+            self.mov(child, from, to);
         }
     }