  In this note we construct an infinite-dimensional Lie group structure on the
group of vertical bisections of a regular Lie groupoid. We then identify the
Lie algebra of this group and discuss regularity properties (in the sense of
Milnor) for these Lie groups. If the groupoid is locally trivial, i.e. a gauge
groupoid, the vertical bisections coincide with the gauge group of the
underlying bundle. Hence the construction recovers the well known Lie group
structure of the gauge groups. To establish the Lie theoretic properties of the
vertical bisections of a Lie groupoid over a non-compact base, we need to
generalise the Lie theoretic treatment of Lie groups of bisections for Lie
groupoids over non-compact bases.
