fix moving items in sln explorer

src/SharpIDE.Godot/Features/SolutionExplorer/SolutionExplorerPanel.cs

@@ -326,18 +326,9 @@ public partial class SolutionExplorerPanel : MarginContainer
 			newStartingIndex += folderCount;
 		}
 		
-		var treeParent = treeItem.GetParent()!;
 		await this.InvokeAsync(() =>
 		{
-			// The API for moving TreeItems is painful - we can only move an Item before or after another item
+			treeItem.MoveToIndexInParent(oldStartingIndex, newStartingIndex);
-			treeParent.RemoveChild(treeItem);
-			var newItem = tree.CreateItem(treeParent, newStartingIndex);
-			newItem.SetText(0, treeItem.GetText(0));
-			newItem.SetIcon(0, treeItem.GetIcon(0));
-			newItem.SetMetadata(0, treeItem.GetMetadata(0));
-			if (isFile) newItem.SetCustomColor(0, treeItem.GetCustomColor(0));
-			treeItemContainer.Value = newItem;
-			treeItem.Free();
 		});
 	}
 

src/SharpIDE.Godot/NodeExtensions.cs

@@ -52,6 +52,17 @@ public static class NodeExtensions
             }
             return null;
         }
+        public void MoveToIndexInParent(int currentIndex, int newIndex)
+        {
+            var parent = treeItem.GetParent()!;
+            if (newIndex == currentIndex) throw new ArgumentException("New index is the same as current index", nameof(newIndex));
+
+            var target = parent.GetChild(newIndex);
+            if (newIndex < currentIndex)
+                treeItem.MoveBefore(target);
+            else
+                treeItem.MoveAfter(target);
+        }
     }
     extension(Node node)
     {