diff --git a/src/components/widgets/lively-window-docking.js b/src/components/widgets/lively-window-docking.js
index 216674718..bd44d9d7b 100644
--- a/src/components/widgets/lively-window-docking.js
+++ b/src/components/widgets/lively-window-docking.js
@@ -261,6 +261,35 @@ export default class LivelyWindowDocking extends Morph {
     }
   }
   
+  resizeMySlot(window, newSize) {
+    return; // @debug
+    var slot = this.availableDockingAreas.find((area) => (area.window == window)); // recheck diff between var and let
+    // lively.notify("Resize slot called");
+    if (slot) {
+      this.availableDockingAreas.forEach(ea => {
+      // debugger; tabbed wrapper closing detection still fails...
+      if (!ea.window || !(ea.window.parentElement)) {
+        var newBounds = null;
+        if (ea.bounds.left() == slot.bounds.left() && ea.bounds.width == slot.bounds.width) { // vertical setup
+          if (ea.bounds.top() + ea.bounds.height == slot.bounds.top()) { // ea top() of slot
+            newBounds = rect(ea.bounds.left(), ea.bounds.top(), ea.bounds.width, ea.bounds.height + slot.bounds.height);
+          } else if (slot.bounds.top() + slot.bounds.height == ea.bounds.top()) { // ea bottom of slot
+            newBounds = rect(slot.bounds.left(), slot.bounds.top(), slot.bounds.width, slot.bounds.height + ea.bounds.height);
+          }
+        } else if (ea.bounds.top() == slot.bounds.top() && ea.bounds.height == slot.bounds.height) { // horizontal setup
+          if (ea.bounds.left() + ea.bounds.width == slot.bounds.left()) { // ea left() of slot
+            newBounds = rect(ea.bounds.left(), ea.bounds.top(), ea.bounds.width + slot.bounds.width, ea.bounds.height);
+          } else if (slot.bounds.left() + slot.bounds.width == ea.bounds.left()) { // ea right of slot
+            newBounds = rect(slot.bounds.left(), slot.bounds.top(), slot.bounds.width + ea.bounds.width, slot.bounds.height);
+          }
+        }
+      }
+    });
+      // only finally resize it's own slot after each neighboring slot has been accounted for. expect newSize to be compatible with bounds?
+      slot.bounds = newSize;
+    }
+  }
+  
   tryAdjoiningEmptySlots(slot) {
     this.availableDockingAreas.forEach(ea => {
       // debugger; tabbed wrapper closing detection still fails...
diff --git a/src/components/widgets/lively-window.js b/src/components/widgets/lively-window.js
index f5e6005ab..38ef6d13a 100644
--- a/src/components/widgets/lively-window.js
+++ b/src/components/widgets/lively-window.js
@@ -153,6 +153,7 @@ export default class Window extends Morph {
       this.addEventListener('dblclick', evt => { this.onDoubleClick(evt); });
       this.get('.window-close').addEventListener('click', evt => { this.onCloseButtonClicked(evt); });
       this.addEventListener('keyup', evt => { this.onKeyUp(evt); });
+      
     } catch (err) {
       console.log("Error, binding events! Continue anyway!", err)
     }
@@ -487,7 +488,6 @@ export default class Window extends Morph {
   
   
   onWindowMouseMove(evt) {    
-    //lively.showEvent(evt)
     
     if (this.dragging) {
       evt.preventDefault();
@@ -530,8 +530,12 @@ export default class Window extends Morph {
   }
 
   onExtentChanged(evt) {
+    console.log(evt); // evt has no content? => current bounds must already have been refreshed
     if (this.target) {
       this.target.dispatchEvent(new CustomEvent("extent-changed"));
+      if (this.isDocked()) {
+        lively.windowDocking.resizeMySlot(this, evt);
+      }
     }
   }
 
@@ -606,7 +610,8 @@ export default class Window extends Morph {
         this.target.dispatchEvent(new CustomEvent("extent-changed"))
       this.classList.add("docked")
     
-    this.displayResizeHandle(!this.isDocked())
+    // DO display resize handles to change slot sizes. Could be made custom in the future to disallow out-of-bounds dragging
+    this.displayResizeHandle(this.isDocked())
   }
   
   undockMe() {