To reproduce:

Add a RadRibbonBar to a Form. Add a RadTextBox to the bottom of the Form. Start the application, click the textbox and press the alt key. You will see that the focus will be taken away. This does not allow you to input key combinations into RadTextBox, such as Alt + 457.


Workaround:

Use the following custom RadRibbonBar:

public class MyRadRibbonBar : RadRibbonBar
{
    protected override ComponentInputBehavior CreateBehavior()
    {
        return new MyRibbonBarInputBehavior(this);
    }


    public override string ThemeClassName
    {
        get
        {
            return typeof(RadRibbonBar).FullName;
        }
        set
        {
        }
    }
}


class MyRibbonBarInputBehavior : RadRibbonBar.RibbonBarInputBehavior
{
    public MyRibbonBarInputBehavior(RadRibbonBar owner)
        : base(owner)
    {
    }


    protected override bool SetInternalKeyMapFocus()
    {
        if ((this.Owner as RadRibbonBar).ContainsFocus)
        {
            return base.SetInternalKeyMapFocus();
        }


        return false;
    }
}