refactor: (core/TabControl) tab close button and close handling - #400

'PipsPagerTemplateSettings.Dispatcher' hides inherited member 'DispatcherObject.Dispatcher'. Use the new keyword if hiding was intended.

The annotation for nullable reference types should only be used in code within a '#nullable' annotations context.

The annotation for nullable reference types should only be used in code within a '#nullable' annotations context.

The annotation for nullable reference types should only be used in code within a '#nullable' annotations context.

'FormattedText.FormattedText(string, CultureInfo, FlowDirection, Typeface, double, Brush)' is obsolete: 'Use the PixelsPerDip override'

The switch expression does not handle some values of its input type (it is not exhaustive) involving an unnamed enum value. For example, the pattern '(System.Windows.Controls.ExpandDirection)4' is not covered.

The variable 'e' is declared but never used

The switch expression does not handle some values of its input type (it is not exhaustive) involving an unnamed enum value. For example, the pattern '(System.Windows.Controls.ExpandDirection)4' is not covered.

'FormattedText.FormattedText(string, CultureInfo, FlowDirection, Typeface, double, Brush)' is obsolete: 'Use the PixelsPerDip override'