diff --git a/src/core/Elsa.Abstractions/Services/IWorkflowScheduler.cs b/src/core/Elsa.Abstractions/Services/IWorkflowScheduler.cs
deleted file mode 100644
index 96298bf9f..000000000
--- a/src/core/Elsa.Abstractions/Services/IWorkflowScheduler.cs
+++ /dev/null
@@ -1,50 +0,0 @@
-// using System;
-// using System.Collections.Generic;
-// using System.Threading;
-// using System.Threading.Tasks;
-// using Elsa.Models;
-// using Elsa.Triggers;
-//
-// namespace Elsa.Services
-// {
-//     public interface IWorkflowScheduler
-//     {
-//         /// <summary>
-//         /// Schedules new and existing instances matching the specified trigger.
-//         /// </summary>
-//         Task TriggerWorkflowsAsync<TTrigger>(Func<TTrigger, bool> predicate, object? input = default, string? correlationId = default, string? contextId = default, CancellationToken cancellationToken = default) where TTrigger : ITrigger;
-//
-//         /// <summary>
-//         /// Schedules the specified workflow instance for execution.
-//         /// </summary>
-//         Task ScheduleWorkflowInstanceAsync(string instanceId, string? activityId = default, object? input = default, CancellationToken cancellationToken = default);
-//
-//         /// <summary>
-//         /// Creates new workflow instances of the specified workflow definition for each start activity and schedules it for execution.
-//         /// </summary>
-//         Task<IEnumerable<WorkflowInstance>> ScheduleWorkflowDefinitionAsync(
-//             string definitionId, 
-//             string? tenantId, 
-//             object? input = default, 
-//             string? correlationId = default, 
-//             string? contextId = default,
-//             CancellationToken cancellationToken = default);
-//
-//         /// <summary>
-//         /// Creates a new workflow instances of the specified workflow definition for the specified start activity and schedules it for execution.
-//         /// </summary>
-//         Task<IEnumerable<WorkflowInstance>> ScheduleWorkflowDefinitionAsync(
-//             string definitionId,
-//             string activityId,
-//             string? tenantId,
-//             object? input = default,
-//             string? correlationId = default,
-//             string? contextId = default,
-//             CancellationToken cancellationToken = default);
-//
-//         /// <summary>
-//         /// Schedules new workflows that start with the specified activity type or are blocked on the specified activity type.
-//         /// </summary>
-//         Task TriggerWorkflowsAsync(string activityType, object? input = default, string? correlationId = default, string? contextId = default, CancellationToken cancellationToken = default);
-//     }
-// }
\ No newline at end of file
diff --git a/src/designer/elsa-workflows-studio/src/components.d.ts b/src/designer/elsa-workflows-studio/src/components.d.ts
index ab73ede4a..cf2f48803 100644
--- a/src/designer/elsa-workflows-studio/src/components.d.ts
+++ b/src/designer/elsa-workflows-studio/src/components.d.ts
@@ -5,7 +5,7 @@
  * It contains typing information for all components that exist in this project.
  */
 import { HTMLStencilElement, JSXBase } from "@stencil/core/internal";
-import { ActivityDefinitionProperty, ActivityDescriptor, ActivityPropertyDescriptor, VersionOptions, WorkflowBlueprint, WorkflowDefinition, WorkflowExecutionLogRecord, WorkflowModel } from "./models";
+import { ActivityDefinitionProperty, ActivityDescriptor, ActivityModel, ActivityPropertyDescriptor, VersionOptions, WorkflowBlueprint, WorkflowDefinition, WorkflowExecutionLogRecord, WorkflowModel } from "./models";
 import { LocationSegments, MatchResults, RouterHistory } from "@stencil/router";
 import { MenuItem } from "./components/controls/elsa-context-menu/models";
 import { DropdownButtonItem, DropdownButtonOrigin } from "./components/controls/elsa-dropdown-button/models";
@@ -35,6 +35,7 @@ export namespace Components {
     }
     interface ElsaDesignerTree {
         "model": WorkflowModel;
+        "selectedActivityIds": Array<string>;
     }
     interface ElsaDropdownButton {
         "icon"?: any;
@@ -487,7 +488,10 @@ declare namespace LocalJSX {
     }
     interface ElsaDesignerTree {
         "model"?: WorkflowModel;
+        "onActivityDeselected"?: (event: CustomEvent<ActivityModel>) => void;
+        "onActivitySelected"?: (event: CustomEvent<ActivityModel>) => void;
         "onWorkflow-changed"?: (event: CustomEvent<WorkflowModel>) => void;
+        "selectedActivityIds"?: Array<string>;
     }
     interface ElsaDropdownButton {
         "icon"?: any;
diff --git a/src/designer/elsa-workflows-studio/src/components/designers/tree/elsa-designer-tree/elsa-designer-tree.tsx b/src/designer/elsa-workflows-studio/src/components/designers/tree/elsa-designer-tree/elsa-designer-tree.tsx
index 8f0864043..c8d730dec 100644
--- a/src/designer/elsa-workflows-studio/src/components/designers/tree/elsa-designer-tree/elsa-designer-tree.tsx
+++ b/src/designer/elsa-workflows-studio/src/components/designers/tree/elsa-designer-tree/elsa-designer-tree.tsx
@@ -18,6 +18,8 @@ import {registerClickOutside} from 'stencil-click-outside';
 import state from '../../../../utils/store';
 import uuid = jsPlumb.jsPlumbUtil.uuid;
 import {ActivityIcon} from '../../../icons/activity-icon';
+import {languages} from "monaco-editor";
+import css = languages.css;
 
 @Component({
   tag: 'elsa-designer-tree',
@@ -27,7 +29,10 @@ import {ActivityIcon} from '../../../icons/activity-icon';
 })
 export class ElsaWorkflowDesigner {
   @Prop() model: WorkflowModel = {activities: [], connections: [], persistenceBehavior: WorkflowPersistenceBehavior.WorkflowBurst};
+  @Prop() selectedActivityIds: Array<string> = [];
   @Event({eventName: 'workflow-changed', bubbles: true, composed: true, cancelable: true}) workflowChanged: EventEmitter<WorkflowModel>;
+  @Event() activitySelected: EventEmitter<ActivityModel>;
+  @Event() activityDeselected: EventEmitter<ActivityModel>;
   @State() workflowModel: WorkflowModel;
 
   el: HTMLElement;
@@ -43,6 +48,7 @@ export class ElsaWorkflowDesigner {
   parentActivityId?: string;
   parentActivityOutcome?: string;
   activityDisplayContexts: Map<ActivityDesignDisplayContext> = {};
+  selectedActivities: Map<ActivityModel> = {};
 
   @State() contextMenu: {
     shown: boolean;
@@ -70,6 +76,20 @@ export class ElsaWorkflowDesigner {
     this.workflowModel = newValue;
   }
 
+  @Watch('selectedActivityIds')
+  handleSelectedActivityIdsChanged(newValue: Array<string>) {
+    debugger;
+    const ids = newValue || [];
+    const selectedActivities = this.workflowModel.activities.filter(x => ids.includes(x.activityId));
+    const map: Map<ActivityModel> = {};
+
+    for (const activity of selectedActivities)
+      map[activity.activityId] = activity;
+
+    this.selectedActivities = map;
+    this.rerenderTree();
+  }
+
   handleEditActivity(activity: ActivityModel) {
     this.showActivityEditor(activity, true);
   }
@@ -197,7 +217,7 @@ export class ElsaWorkflowDesigner {
     this.innerD3Selected = d3.select(this.inner);
     setTimeout(() => {
       this.rerenderTree()
-    }, 400)
+    }, 600)
   }
 
   componentWillRender() {
@@ -222,7 +242,7 @@ export class ElsaWorkflowDesigner {
       eventBus.emit(EventTypes.ActivityDesignDisplaying, this, displayContext);
       displayContexts[model.activityId] = displayContext;
     }
-    
+
     this.activityDisplayContexts = displayContexts;
   }
 
@@ -355,9 +375,27 @@ export class ElsaWorkflowDesigner {
 
     d3.selectAll('.node.activity').each((n: any) => {
       const node = this.graph.node(n) as any;
+      const activity = node.activity;
+      const activityId = activity.activityId;
+
       d3.select(node.elem).on('click', () => {
+        // If a parent activity was selected to connect to:
         if (this.parentActivityId && this.parentActivityOutcome) {
-          this.addConnection(this.parentActivityId, node.activity.activityId, this.parentActivityOutcome);
+          this.addConnection(this.parentActivityId, activityId, this.parentActivityOutcome);
+        } else {
+          // When clicking an activity:
+          if (!!this.selectedActivities[activityId])
+            delete this.selectedActivities[activityId];
+          else {
+            for (const key in this.selectedActivities) {
+              this.activityDeselected.emit(this.selectedActivities[key]);
+            }
+            this.selectedActivities = {};
+            this.selectedActivities[activityId] = activity;
+            this.activitySelected.emit(activity);
+          }
+
+          this.rerenderTree();
         }
       });
       d3.select(node.elem)
@@ -399,8 +437,9 @@ export class ElsaWorkflowDesigner {
 
   renderActivity(activity: ActivityModel) {
     const displayContext = this.activityDisplayContexts[activity.activityId] || undefined;
+    const cssClass = !!this.selectedActivities[activity.activityId] ? 'border-blue-600' : 'border-white hover:border-blue-600'
     return `<div id=${`activity-${activity.activityId}`} 
-    class="activity border-2 border-solid border-white rounded bg-white text-left text-black text-lg hover:border-blue-600 select-none max-w-md shadow-sm relative">
+    class="activity border-2 border-solid rounded bg-white text-left text-black text-lg select-none max-w-md shadow-sm relative ${cssClass}">
       <div class="p-5">
         <div class="flex justify-between space-x-8">
           <div class="flex-shrink-0">
@@ -429,9 +468,11 @@ export class ElsaWorkflowDesigner {
 
   renderActivityBody(description: string | null) {
     if (!description) return '';
-    return `<div class="p-6 text-gray-400 text-sm border-t border-t-solid">
-              ${description}
-            </div>`;
+    return (
+      `<div class="p-6 text-gray-400 text-sm border-t border-t-solid">
+        ${description}
+      </div>`
+    );
   }
 
   // private onActivitySelected(e: CustomEvent<ActivityModel>) {
@@ -445,8 +486,8 @@ export class ElsaWorkflowDesigner {
   render() {
     return (
       <Host class="workflow-canvas flex-1 flex" ref={el => (this.el = el)}>
-        <svg ref={el => (this.svg = el)} id="svg" style={{ height: 'calc(100vh - 64px)', width: '100%', pointerEvents: this.contextMenu.shown ? 'none' : '' }}>
-          <g ref={el => (this.inner = el)} />
+        <svg ref={el => (this.svg = el)} id="svg" style={{height: 'calc(100vh - 64px)', width: '100%', pointerEvents: this.contextMenu.shown ? 'none' : ''}}>
+          <g ref={el => (this.inner = el)}/>
         </svg>
         <div
           data-transition-enter="transition ease-out duration-100"
@@ -456,7 +497,7 @@ export class ElsaWorkflowDesigner {
           data-transition-leave-start="transform opacity-100 scale-100"
           data-transition-leave-end="transform opacity-0 scale-95"
           class={`${this.contextMenu.shown ? '' : 'hidden'} context-menu z-10 mx-3 w-48 mt-1 rounded-md shadow-lg`}
-          style={{ position: 'absolute', left: `${this.contextMenu.x}px`, top: `${this.contextMenu.y - 64}px` }}
+          style={{position: 'absolute', left: `${this.contextMenu.x}px`, top: `${this.contextMenu.y - 64}px`}}
           ref={el =>
             registerClickOutside(this, el, () => {
               this.handleContextMenuChange(0, 0, false, null);
@@ -487,7 +528,6 @@ export class ElsaWorkflowDesigner {
             </div>
           </div>
         </div>
-        {/* <div innerHTML={<ActivityIcon />} /> */}
       </Host>
     );
   }
diff --git a/src/designer/elsa-workflows-studio/src/components/screens/workflow-instance-viewer/elsa-workflow-instance-viewer-screen/elsa-workflow-instance-viewer-screen.tsx b/src/designer/elsa-workflows-studio/src/components/screens/workflow-instance-viewer/elsa-workflow-instance-viewer-screen/elsa-workflow-instance-viewer-screen.tsx
index 0de858eb2..759137a33 100644
--- a/src/designer/elsa-workflows-studio/src/components/screens/workflow-instance-viewer/elsa-workflow-instance-viewer-screen/elsa-workflow-instance-viewer-screen.tsx
+++ b/src/designer/elsa-workflows-studio/src/components/screens/workflow-instance-viewer/elsa-workflow-instance-viewer-screen/elsa-workflow-instance-viewer-screen.tsx
@@ -169,7 +169,7 @@ export class ElsaWorkflowInstanceViewerScreen {
   }
 
   onActivityDeselected(e: CustomEvent<ActivityModel>) {
-    if(this.selectedActivityId == e.detail.activityId)
+    if (this.selectedActivityId == e.detail.activityId)
       this.selectedActivityId = null;
 
     this.journal.selectActivityRecord(this.selectedActivityId);
@@ -180,7 +180,7 @@ export class ElsaWorkflowInstanceViewerScreen {
     return (
       <Host class="flex flex-col w-full relative" ref={el => this.el = el}>
         {this.renderCanvas()}
-        <elsa-workflow-instance-journal ref={el => this.journal = el} 
+        <elsa-workflow-instance-journal ref={el => this.journal = el}
                                         workflowInstanceId={this.workflowInstanceId}
                                         serverUrl={this.serverUrl}
                                         activityDescriptors={descriptors}
@@ -196,9 +196,9 @@ export class ElsaWorkflowInstanceViewerScreen {
       <div class="flex-1 flex">
         <elsa-designer-tree model={this.workflowModel}
                             class="flex-1" ref={el => this.designer = el}
-                            // selectedActivityId={this.selectedActivityId}
-                            // onActivitySelected={e => this.onActivitySelected(e)}
-                            // onActivityDeselected={e => this.onActivityDeselected(e)}
+                            selectedActivityIds={[this.selectedActivityId]}
+                            onActivitySelected={e => this.onActivitySelected(e)}
+                            onActivityDeselected={e => this.onActivityDeselected(e)}
         />
       </div>
     );