Adjustable Time Strip view: column resizing

- Column resizing now shows the horizontal resize handle on the Time axis swimlane only. Handle now uses `:height` from the extended overlay lines to extend across all swimlanes.
- TODO: fix regressions in Plan/Gantt view affecting swimlane height and overflow handling.

src/plugins/timeline/TimelineViewLayout.vue

@@ -25,6 +25,8 @@
     <SwimLane
       v-for="timeSystemItem in timeSystems"
       :key="timeSystemItem.timeSystem.key"
+      :canShowResizeHandle="true"
+      :resizeHandleHeight="height"
       class="c-swimlane__time-axis"
     >
       <template #label>

src/ui/components/swim-lane/SwimLane.vue

@@ -56,7 +56,12 @@
           @click="pressOnButton"
         />
       </div>
-      <div class="c-swimlane__handle horizontal" @mousedown="mousedown"></div>
+      <div
+        v-if="canShowResizeHandle"
+        class="c-swimlane__handle horizontal"
+        :style="{ height: `${resizeHandleHeight}px` }"
+        @mousedown="mousedown"
+      ></div>
     </div>
 
     <div
@@ -118,6 +123,19 @@ export default {
         return false;
       }
     },
+    canShowResizeHandle: {
+      type: Boolean,
+      default() {
+        return false;
+      }
+    },
+    resizeHandleHeight: {
+      type: Number,
+      required: false,
+      default() {
+        return 32;
+      }
+    },
     spanRowsCount: {
       type: Number,
       default() {

src/ui/components/swim-lane/swimlane.scss

@@ -55,6 +55,7 @@
   &__handle {
     $size: $handleSize;
     $margin: $handleMargin;
+    z-index: 2;
 
     @include resizeHandleStyle($size, $margin);
 
@@ -69,7 +70,7 @@
     &.horizontal {
       // Resizes in X dimension
       left: auto;
-      right: -1 * $handleHitSize;
+      right: math.floor($handleHitSize * -0.5);
       width: $handleHitSize;
     }
   }
@@ -102,8 +103,7 @@
   }
 
   .is-editing & {
-    // TODO: BETTER SELECTOR TO LIMIT STYLING TO TIME STRIP IN MAIN VIEW, NOT NESTED VIEWS
+    //grid-column-gap: $handleHitSize;
-    grid-column-gap: $handleHitSize;
     .c-swimlane__handle {
       display: block;
     }