image editor: right-click can drag when not used by a tool

Author: mcmonkey4eva

src/wwwroot/js/genpage/helpers/image_editor.js

@@ -520,9 +520,7 @@ class ImageEditor {
         });
         canvas.addEventListener('drop', (e) => this.handleCanvasImageDrop(e));
         canvas.addEventListener('contextmenu', (e) => {
-            if (this.activeTool && this.activeTool.onContextMenu(e)) {
-                e.preventDefault();
-            }
+            e.preventDefault();
         });
         this.ctx = canvas.getContext('2d');
         canvas.style.cursor = 'none';
@@ -724,16 +722,20 @@ class ImageEditor {
     }
 
     onMouseDown(e) {
+        // 1 = middle, 2 = right
         if (this.altDown || e.button == 1) {
             this.handleAltDown();
         }
+        if (e.button == 2 && this.activeTool && !this.activeTool.onContextMenu(e)) {
+            this.handleAltDown();
+        }
         this.mouseDown = true;
         this.activeTool.onMouseDown(e);
         this.redraw();
     }
 
     onMouseUp(e) {
-        if (e.button == 1) {
+        if (e.button == 1 || e.button == 2) {
             this.handleAltUp();
         }
         this.mouseDown = false;