Allow Mouse Wheel scroll on a TabPage Control

Question

A TabPage of a TabControl is populated with using a XML source. Once the XML contents are loaded into the TabPage, two ScrollBars appear on either side of the TabPage, to allow a user to scroll.
The user cannot scroll with the Mouse Wheel, though. I have checked the properties of the TabPage Control but I cannot find any property to assist with this.

Someone suggested to handle the MouseWheel event or override OnMouseWheel , but I'm not sure how this can be applied.
The gist of this is simple, how do I activate the Mouse wheel scroll on a tab page?

public partial class ModifyTransformerContentsView : Form
{
    private readonly ITransformerConfigurationViewModel ViewModel;

    public ModifyTransformerContentsView(ITransformerConfigurationViewModel viewModel)
    {
        InitializeComponent();

        this.ViewModel = viewModel;
        this.ViewModel.Notify += this.OnNotify;

        this.xmlEditExampleStdfOutFile.SetFormateText(File.ReadAllText(this.ViewModel.SampleProcessingFilePath));
        this.xmlEditExampleStdfOutFile.ReadOnly = true;

        this.rtbXsl.SetFormateText(File.ReadAllText(this.ViewModel.TransformerFilePath));
        this.rtbXsl.ReadOnly = false;
        this.rtbXsl.RichTextBox.ClearUndo();

        this.btnSave.Enabled = false;

        this.rtbCheatSheet.Text = File.ReadAllText(this.ViewModel.CheatSheetFilePath);
    }

    private void OnValidateClick(object sender, System.EventArgs e)
    {
        this.ViewModel.SetTemporaryTransformerFileContents(this.rtbXsl.Text);

        this.ViewModel.ValidateXsl(this.rtbXsl.Text,
            validationSuccessful =>
            {
                this.btnSave.Enabled = validationSuccessful;

                this.rtbExampleOutputFileContents.SetFormateText(this.ViewModel.ExampleFileOutputContents);
            });
    }

    private void OnSaveClick(object sender, System.EventArgs e) => this.ViewModel.Save(this.rtbXsl.Text);

    private void OnNotify(NotificationEventArgs obj)
    {
        switch (obj.NotificationType)
        {
            case NotificationType.Info:
                MessageBox.Show(obj.Message, "Information", MessageBoxButtons.OK, MessageBoxIcon.Information);

                if (obj.Exit)
                {
                    this.Close();
                }

                break;
            case NotificationType.Warning:
                MessageBox.Show(obj.Message, "Warning", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                break;
            case NotificationType.Error:
                MessageBox.Show(obj.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);

                if (obj.Exit)
                {
                    this.Close();
                }

                break;
        }
    }

    private void ModifyTransformerContentsView_FormClosing(object sender, FormClosingEventArgs e)
        => this.ViewModel.DeleteTemporaryModifiedTransformerFile();

    private void OnButtonCheatSheetSaveClick(object sender, System.EventArgs e) =>
        this.ViewModel.SaveCheatSheet(rtbCheatSheet.Text);

    private void ModifyTransformerContentsView_Load(object sender, System.EventArgs e)
    {

    }
}

Any assistance would be appreciated.

Answer 1

The TagPage Control class is derived from the Panel class.
This type of Control is not selectable ( ControlStyles.Selectable is set to false in its Constructor), so it doesn't receive focus and cannot be selected with a Mouse click.

You can override this behavior in different ways. Three simple methods:

1. Build a Custom Control derived from TabPage then:

   • in its Constructor, call SetStyle() :

      SetStyle(ControlStyles.Selectable | ControlStyles.UserMouse | ControlStyles.StandardClick, true);

   • Create an instance of this Custom Control and add it to the TabPages of a TabControl

2. Build a Custom Control derived from Panel:

   • Set the same ControlStyles in its Constructor
   • Build the Control, find it in the ToolBox and drop it inside a TabPage, then set Dock = DockStyle.Fill and AutoScroll = true (or do this directly in the Custom Control class).
   • Add all child Controls to this Panel.

3. Using Reflection, get the non-public SetStyle method of a TabPage and use MethodInfo.Invoke() to change the values. eg,:

    using System.Reflection; var flags = BindingFlags.NonPublic | BindingFlags.Instance; var method = tabPage1.GetType().GetMethod("SetStyle", flags); var newStyles = ControlStyles.Selectable | ControlStyles.UserMouse; method.Invoke(tabPage1, new object[] { newStyles, true });

   You can do this to all TabPages in a loop.