A heavy-handed fix for middlemouse pan (#8865)

Sometimes, middle mouse clicks would fail to initiate a canvas pan,
depending on the target of the initial pan. This PR adds a capturing
event handler to the transform pane that forwards the pointer event to
canvas if
- It is a middle mouse click
- The target element is not a focused text element

Resolves #6911

While testing this, I encountered infrequent cases of "some nodes
unintentionally translating continually to the left". Reproduction was
too unreliable to properly track down, but did appear unrelated to this
PR.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8865-A-heavy-handed-fix-for-middlemouse-pan-3076d73d365081ea9a4ddd5786fc647a)
by [Unito](https://www.unito.io)

src/components/graph/GraphCanvas.vue

@@ -60,6 +60,9 @@
     v-if="shouldRenderVueNodes && comfyApp.canvas && comfyAppReady"
     :canvas="comfyApp.canvas"
     @wheel.capture="canvasInteractions.forwardEventToCanvas"
+    @pointerdown.capture="forwardPanEvent"
+    @pointerup.capture="forwardPanEvent"
+    @pointermove.capture="forwardPanEvent"
   >
     <!-- Vue nodes rendered based on graph nodes -->
     <LGraphNode
@@ -114,6 +117,7 @@ import {
 } from 'vue'
 import { useI18n } from 'vue-i18n'
 
+import { isMiddlePointerInput } from '@/base/pointerUtils'
 import LiteGraphCanvasSplitterOverlay from '@/components/LiteGraphCanvasSplitterOverlay.vue'
 import TopMenuSection from '@/components/TopMenuSection.vue'
 import BottomPanel from '@/components/bottomPanel/BottomPanel.vue'
@@ -160,6 +164,7 @@ import { ChangeTracker } from '@/scripts/changeTracker'
 import { IS_CONTROL_WIDGET, updateControlWidgetLabel } from '@/scripts/widgets'
 import { useColorPaletteService } from '@/services/colorPaletteService'
 import { useNewUserService } from '@/services/useNewUserService'
+import { shouldIgnoreCopyPaste } from '@/workbench/eventHelpers'
 import { storeToRefs } from 'pinia'
 
 import { useBootstrapStore } from '@/stores/bootstrapStore'
@@ -540,4 +545,13 @@ onMounted(async () => {
 onUnmounted(() => {
   vueNodeLifecycle.cleanup()
 })
+function forwardPanEvent(e: PointerEvent) {
+  if (
+    (shouldIgnoreCopyPaste(e.target) && document.activeElement === e.target) ||
+    !isMiddlePointerInput(e)
+  )
+    return
+
+  canvasInteractions.forwardEventToCanvas(e)
+}
 </script>