private void LeftDown(MouseButtonEventArgs e)
{
bool onlyCtrl = Keyboard.Modifiers == ModifierKeys.Control;
bool onlyShift = Keyboard.Modifiers == ModifierKeys.Shift;
bool sourceIsThumb = ((e.OriginalSource as FrameworkElement).TemplatedParent) is Thumb;
Point sheetPoint = e.GetPosition(_sheetController.State.OverlaySheet.GetParent() as FrameworkElement);
ImmutablePoint sheetPosition = new ImmutablePoint(sheetPoint.X, sheetPoint.Y);
Point rootPoint = e.GetPosition(this);
ImmutablePoint rootPosition = new ImmutablePoint(rootPoint.X, rootPoint.Y);
var args = new InputArgs()
{
OnlyControl = onlyCtrl,
OnlyShift = onlyShift,
SourceType = sourceIsThumb ? ItemType.Thumb : ItemType.None,
SheetPosition = sheetPosition,
RootPosition = rootPosition,
Handled = (handled) => e.Handled = handled,
Delta = 0,
Button = InputButton.Left,
Clicks = 1
};
_sheetController.LeftDown(args);
}