fix(browser): fix pane close operation in gotk4 migration

Fixed GTK assertion error when closing split panes by properly handling
widget unparenting for gotk4 API.

Key changes:
- Removed incorrect nil checks after WidgetUnparent() in attachRoot()
  In gotk4, Go object references remain valid after unparent, unlike
  CGO where C pointers could become invalid

- Added manual unparenting of sibling from parent paned before promotion
  GTK4 auto-unparents for paned operations (SetStartChild/SetEndChild)
  but window.SetChild() requires widgets to already be unparented

- Updated comments to explain gotk4/GTK4 behavior differences

This fixes the GTK error:
"gtk_window_set_child: assertion 'child == NULL || priv->child == child
|| gtk_widget_get_parent (child) == NULL' failed"

Pane close operations now complete successfully without killing both panes.

commit: 58f535ab423075b9d05b2184504c086fdb240bda
author: bamen · 12mo ago · 2025-10-10 05:50 UTC
parent: a1a9d2d
signature: unsigned

1 file · +23 -14

M internal/app/browser/workspace_pane_ops.go +23 -14


@@ -1051,13 +1051,12 @@ func (wm WorkspaceManager) attachRoot(root paneNode) {
1051	1051		// No need for manual Ref()/Unref() calls
1052	1052
1053	1053		// Detach from previous container (paned, stack, etc.) before replacing the window child.
	1054	+	// While GTK4 auto-unparents for paned operations, window.SetChild requires manual unparent
1054	1055		if parent := webkit.WidgetGetParent(root.container); parent != nil {
1055	1056		log.Printf("[workspace] unparenting widget %p from parent %p before window attach", root.container, parent)
1056	1057		webkit.WidgetUnparent(root.container)
1057		-	if root.container == nil {
1058		-	log.Printf("[workspace] WARNING: widget %p became invalid during unparent; aborting attachRoot", root.container)
1059		-	return
1060		-	}
	1058	+	// Note: In gotk4, the Go object reference remains valid after unparent
	1059	+	// Only the GTK parent relationship is cleared
1061	1060		}
1062	1061
1063	1062		// Clear any existing window child to avoid GTK warnings when swapping roots.

@@ -1068,11 +1067,7 @@ func (wm WorkspaceManager) attachRoot(root paneNode) {
1068	1067		webkit.WidgetSetVExpand(root.container, true)
1069	1068		}
1070	1069
1071		-	if root.container == nil {
1072		-	log.Printf("[workspace] WARNING: widget %p invalid prior to window attach", root.container)
1073		-	return
1074		-	}
1075		-
	1070	+	// GTK4 will automatically unparent root.container from its previous parent when we attach it here
1076	1071		wm.window.SetChild(root.container)
1077	1072		if root.container != nil {
1078	1073		webkit.WidgetQueueAllocate(root.container)

@@ -1251,11 +1246,25 @@ func (wm WorkspaceManager) closePane(node paneNode) (*paneNode, error) {
1251	1246		}
1252	1247		}
1253	1248
1254		-	// STEP 5: Promote sibling in-place (tree structure)
	1249	+	// STEP 5: Unparent sibling from parent paned BEFORE promotion
	1250	+	// The sibling needs to be detached from the parent paned before we can attach it elsewhere
	1251	+	if sibling.container != nil && parent.container != nil {
	1252	+	if parentPaned, ok := parent.container.(*gtk.Paned); ok && parentPaned != nil {
	1253	+	if parent.left == sibling {
	1254	+	parentPaned.SetStartChild(nil)
	1255	+	} else if parent.right == sibling {
	1256	+	parentPaned.SetEndChild(nil)
	1257	+	}
	1258	+	log.Printf("[workspace] unparented sibling container %p from parent paned %p", sibling.container, parent.container)
	1259	+	}
	1260	+	}
	1261	+
	1262	+	// STEP 6: Promote sibling in-place (tree structure)
1255	1263		wm.promoteSibling(grandparent, parent, sibling)
1256	1264
1257		-	// STEP 6: GTK handles all reparenting automatically
1258		-	// PanedSetStartChild/EndChild and window.SetChild auto-unparent widgets
	1265	+	// STEP 7: GTK widget reparenting
	1266	+	// For paned containers: GTK4 PanedSetStartChild/EndChild auto-unparent from current parent
	1267	+	// For window: we already manually unparented above, so now we can safely attach
1259	1268		wm.swapContainers(grandparent, sibling)
1260	1269
1261	1270		// Reconnect the promoted sibling's rendering pipeline after GTK reparenting.

@@ -1273,14 +1282,14 @@ func (wm WorkspaceManager) closePane(node paneNode) (*paneNode, error) {
1273	1282		}, sibling)
1274	1283		}
1275	1284
1276		-	// STEP 7: Check if grandparent now has only one child (cascade promotion needed)
	1285	+	// STEP 8: Check if grandparent now has only one child (cascade promotion needed)
1277	1286		if grandparent != nil && ((grandparent.left == nil) != (grandparent.right == nil)) {
1278	1287		// Grandparent has exactly one child - it should be promoted too
1279	1288		log.Printf("[workspace] Grandparent %p now has only one child, cascading promotion", grandparent)
1280	1289		wm.cascadePromotion(grandparent)
1281	1290		}
1282	1291
1283		-	// STEP 8: Cleanup & focus
	1292	+	// STEP 9: Cleanup & focus
1284	1293		wm.cleanupPane(node, ctx.Generation())
1285	1294		wm.decommissionParent(parent, ctx.Generation())
1286	1295		if sibling != nil {

 	// No need for manual Ref()/Unref() calls
 	// Detach from previous container (paned, stack, etc.) before replacing the window child.
+	// While GTK4 auto-unparents for paned operations, window.SetChild requires manual unparent
 	if parent := webkit.WidgetGetParent(root.container); parent != nil {
 		log.Printf("[workspace] unparenting widget %p from parent %p before window attach", root.container, parent)
 		webkit.WidgetUnparent(root.container)
-		if root.container == nil {
+		// Note: In gotk4, the Go object reference remains valid after unparent
-			log.Printf("[workspace] WARNING: widget %p became invalid during unparent; aborting attachRoot", root.container)
+		// Only the GTK parent relationship is cleared
-			return
-		}
 	}
 	// Clear any existing window child to avoid GTK warnings when swapping roots.
 		webkit.WidgetSetVExpand(root.container, true)
 	}
-	if root.container == nil {
+	// GTK4 will automatically unparent root.container from its previous parent when we attach it here
-		log.Printf("[workspace] WARNING: widget %p invalid prior to window attach", root.container)
-		return
-	}
 	wm.window.SetChild(root.container)
 	if root.container != nil {
 		webkit.WidgetQueueAllocate(root.container)
 		}
 	}
-	// STEP 5: Promote sibling in-place (tree structure)
+	// STEP 5: Unparent sibling from parent paned BEFORE promotion
+	// The sibling needs to be detached from the parent paned before we can attach it elsewhere
+	if sibling.container != nil && parent.container != nil {
+		if parentPaned, ok := parent.container.(*gtk.Paned); ok && parentPaned != nil {
+			if parent.left == sibling {
+				parentPaned.SetStartChild(nil)
+			} else if parent.right == sibling {
+				parentPaned.SetEndChild(nil)
+			}
+			log.Printf("[workspace] unparented sibling container %p from parent paned %p", sibling.container, parent.container)
+		}
+	}
+	// STEP 6: Promote sibling in-place (tree structure)
 	wm.promoteSibling(grandparent, parent, sibling)
-	// STEP 6: GTK handles all reparenting automatically
+	// STEP 7: GTK widget reparenting
-	// PanedSetStartChild/EndChild and window.SetChild auto-unparent widgets
+	// For paned containers: GTK4 PanedSetStartChild/EndChild auto-unparent from current parent
+	// For window: we already manually unparented above, so now we can safely attach
 	wm.swapContainers(grandparent, sibling)
 	// Reconnect the promoted sibling's rendering pipeline after GTK reparenting.
 		}, sibling)
 	}
-	// STEP 7: Check if grandparent now has only one child (cascade promotion needed)
+	// STEP 8: Check if grandparent now has only one child (cascade promotion needed)
 	if grandparent != nil && ((grandparent.left == nil) != (grandparent.right == nil)) {
 		// Grandparent has exactly one child - it should be promoted too
 		log.Printf("[workspace] Grandparent %p now has only one child, cascading promotion", grandparent)
 		wm.cascadePromotion(grandparent)
 	}
-	// STEP 8: Cleanup & focus
+	// STEP 9: Cleanup & focus
 	wm.cleanupPane(node, ctx.Generation())
 	wm.decommissionParent(parent, ctx.Generation())
 	if sibling != nil {