Known Design-Time Limitations in .NET Core WinForms and Syncfusion Controls

This article documents known design-time limitations affecting certain controls properties in .NET Core WinForms. These issues are largely caused by the out‑of‑process WinForms Designer architecture, which results in UITypeEditors, collection editors, and smart tags having only limited communication with the design surface.

Control-Specific Known Issues

Docking Manager

DockingManager component is used to host panels and arrange them by docking within the layout. Normally, panels can be added and their dock positions adjusted by dragging the panel header at design time.

However, due to an issue where the incorrect mouse value is updated at design time in .NET Core, the drag-and-drop functionality does not work as expected. As a result, the dock position of panels inside the DockingManager cannot be changed at design time and can only be configured at runtime.

SplashControl

The SplashControl smart tags allow the control to be previewed using the PreviewSplash option. However, in the out‑of‑process WinForms Designer, the designer does not display the design‑time preview of the SplashControl.

RadialMenu

The RadialMenu control contains the ImageCollection property used to add images. However, due to limitations in the CollectionEditor for .NET Core, the ImageCollection property does not function as intended, and images cannot be added at design time.

ChildFrameBarManager

The Bars, Categories, or Items properties are used to add customized toolbar items in the ChildFrameBarManager control. However, the custom UITypeEditor form required for adding items is not supported in the .NET Core, so items cannot be added at design time.

WizardControl and StatusBarAdv

When adding child items to the WizardControl and StatusBarAdv controls using the WizardPages and Panels properties, the CollectionEditor form opens and works properly at design time. However, the editor title is incorrectly displayed as ControlProxy`1 Collection Editor instead of WizardControlPage Collection Editor or StatusBarAdvPanel Collection Editor.

TreeNavigator and RadialMenu

In the TreeNavigator and RadialMenu, child items can be added to a control using the Items property, which displays a custom UITypeEditor form. However, when attempting to add items for child elements via the designer, the default collection editor is shown. This editor adds a default control type instead of TreeMenuItem or RadialMenuItem. Due to this limitation, child items cannot be added to TreeMenuItem and RadialMenuItem.

MultiColumnTreeView

MultiColumnTreeView control exposes a Nodes property in the Properties window, allowing developers to add or modify nodes at design time. When this option is opened, a Custom UiTypeEditor form is displayed. Within this form, each node provides a SubItems property that shows a CollectionEditor form, which allows developers to specify values for additional columns.

However, in the current .NET Core WinForms Designer:

• The SubItems property does not function as intended.
• When attempting to add items to SubItems at design time, the items are not added and do not appear in the designer.

GridControl and GridGroupingControl

In the .NET Framework WinForms Designer, these properties appear as a dropdown with checkboxes, enabling multiple selections and offering a Clear button for resetting selections. In the .NET Core WinForms Designer, these properties are shown as a standard dropdown that allows only a single selection in the Properties window:

• AllowScrollCurrentCellInView
• AllowSelection
• ResizeColsBehavior
• ResizeRowsBehavior
• SelectCellsMouseButtonsMask

In .NET Core WinForms, the GradientColor property is disabled and cannot be configured through the designer in GridControl.

Diagram

In the Diagram control, the collection editor button is not available for properties that rely on UITypeEditor. Because of this limitation, these properties cannot be edited at design time in the Properties window.

• Document
• BackgroundStyle
• ShadowStyle
• Left
• Right
• Center
• DocumentSize
• DocumentScale
• Palette

These limitations are known and documented. They are primarily due to the out-of-process architecture of the .NET Core WinForms designer, which currently restricts certain advanced design-time features. Our team is actively working to enhance design-time support for these properties and controls in future releases. Until these improvements are available, developers are advised to configure the affected properties programmatically in code-behind or during runtime.