Unselect when not in Selection bounding box anymore.

Performance optimisation to only fire event when value actually changed.

Solves #417

packages/react-canvas-core/src/core-models/BaseModel.ts

@@ -98,14 +98,16 @@ export class BaseModel<G extends BaseModelGenerics = BaseModelGenerics> extends
 	}
 
 	setSelected(selected: boolean = true) {
-		this.options.selected = selected;
+		if (this.options.selected !== selected) {
+			this.options.selected = selected;
 
-		this.fireEvent(
-			{
-				isSelected: selected
-			},
-			'selectionChanged'
-		);
+			this.fireEvent(
+				{
+					isSelected: selected
+				},
+				'selectionChanged'
+			);
+		}
 	}
 
 	remove() {

packages/react-canvas-core/src/states/SelectionBoxState.ts

@@ -58,6 +58,8 @@ export class SelectionBoxState extends AbstractDisplacementState {
 				const bounds = ((model as unknown) as ModelGeometryInterface).getBoundingBox();
 				if (rect.containsPoint(bounds.getTopLeft()) && rect.containsPoint(bounds.getBottomRight())) {
 					model.setSelected(true);
+				} else {
+					model.setSelected(false);
 				}
 			}
 		}