reset split ratio on double click (fixes #1377)

terminus-core/src/components/splitTabSpanner.component.ts

@@ -23,6 +23,10 @@ export class SplitTabSpannerComponent {
     constructor (private element: ElementRef) { }
 
     ngAfterViewInit () {
+        this.element.nativeElement.addEventListener('dblclick', () => {
+            this.reset()
+        })
+
         this.element.nativeElement.addEventListener('mousedown', (e: MouseEvent) => {
             this.isActive = true
             const start = this.isVertical ? e.pageY : e.pageX
@@ -49,14 +53,16 @@ export class SplitTabSpannerComponent {
                 diff = Math.max(diff, -this.container.ratios[this.index - 1] + 0.1)
                 diff = Math.min(diff, this.container.ratios[this.index] - 0.1)
 
-                this.container.ratios[this.index - 1] += diff
-                this.container.ratios[this.index] -= diff
-                this.change.emit()
+                if (diff) {
+                    this.container.ratios[this.index - 1] += diff
+                    this.container.ratios[this.index] -= diff
+                    this.change.emit()
+                }
             }
 
-            document.addEventListener('mouseup', offHandler)
+            document.addEventListener('mouseup', offHandler, { passive: true })
             this.element.nativeElement.parentElement.addEventListener('mousemove', dragHandler)
-        })
+        }, { passive: true })
     }
 
     ngOnChanges () {
@@ -79,6 +85,13 @@ export class SplitTabSpannerComponent {
         }
     }
 
+    reset () {
+        const ratio = (this.container.ratios[this.index - 1] + this.container.ratios[this.index]) / 2
+        this.container.ratios[this.index - 1] = ratio
+        this.container.ratios[this.index] = ratio
+        this.change.emit()
+    }
+
     private setDimensions (x: number, y: number, w: number, h: number) {
         this.cssLeft = `${x}%`
         this.cssTop = `${y}%`