# Form
## Form Designer
### Design mode
### ASP.NET editor
Click  in the toolbar to open the ASP.NET code editor, which can be used to define server-side procedures, events, and global variables to handle any specific custom tasks. This feature is mainly intended for ASP.NET server-side development.
{% hint style="info" %}
As of WorkflowGen version 7.19.0, all `default.aspx` files are saved with the `Page Async` property set to `true` (e.g. `<%@ Page Async="true" ... %>`). This allows asynchronous ASP.NET web form development (see the [Using Asynchronous Methods in ASP.NET 4.5](https://docs.microsoft.com/en-us/aspnet/web-forms/overview/performance-and-caching/using-asynchronous-methods-in-aspnet-45) Microsoft article for more information).
{% endhint %}
### JavaScript editor
Click  in the toolbar to open the JavaScript code editor, which can be used to define server-side procedures, events, and global variables to handle any specific custom tasks. This feature is mainly intended for JavaScript client-side development.
### Advanced features
#### Server-side editing mode
Check **Enable server-side editing mode** on the **General** tab in the **Form configuration** panel to activate this mode, which allows form designers to modify the content of the form's C# `runat` server tag (e.g. `