fixes for helper sizing

src/agenda/TimeGridHelperRenderer.ts

@@ -31,6 +31,11 @@ export default class TimeGridHelperRenderer extends HelperRenderer {
           marginLeft: computedStyle.marginLeft,
           marginRight: computedStyle.marginRight
         })
+      } else {
+        applyStyle(seg.el, {
+          left: 0,
+          right: 0
+        })
       }
 
       helperNodes.push(seg.el)
@@ -40,11 +45,11 @@ export default class TimeGridHelperRenderer extends HelperRenderer {
   }
 
   computeSize() {
-    this.component.computeSegVerticals(this.segs)
+    this.component.computeSegVerticals(this.segs || [])
   }
 
   assignSize() {
-    this.component.assignSegVerticals(this.segs)
+    this.component.assignSegVerticals(this.segs || [])
   }
 
 }

src/component/DateComponent.ts

@@ -154,6 +154,10 @@ export default abstract class DateComponent extends Component {
       this.computeHighlightSize()
     }
 
+    if (force || flags.drag || flags.eventResize) {
+      this.computeHelperSize()
+    }
+
     if (force || flags.events) {
       this.computeEventsSize()
     }
@@ -166,6 +170,10 @@ export default abstract class DateComponent extends Component {
       this.assignHighlightSize()
     }
 
+    if (force || flags.drag || flags.eventResize) {
+      this.assignHelperSize()
+    }
+
     if (force || flags.events) {
       this.assignEventsSize()
     }