Change displaying control of collapsed region

Hey everyone,

I want to change the content of the box shown when you collapse an XML comment in C#. By default, a comment like

/// <summary>
/// Foo
/// </summary>
/// <param name="bar">Some argument</param>

is shown as "/// <summary> Foo" when it is collapsed.

I want to change this by showing a well formatted text including also parameters, noted exceptions etc.

What I have tried so far is to provide my own OutliningRegionTag, but the original implementation provided by VS seems to take precedence so my outlining tag is not used.

Is there a way to either
a) change the control of the default outlining implementation or
b) to remove the original outlining of comments entirely?

Thank you sharing any ideas!