  We report results of systematic numerical analysis of collisions between two
and three stable dissipative solitons in the two-dimensional (2D) complex
Ginzburg- Landau equation (CGLE) with the cubic-quintic (CQ) combination of
gain and loss terms. The equation may be realized as a model of a laser cavity
which includes the spatial diffraction, together with the anomalous
group-velocity dispersion (GVD) and spectral filtering acting in the temporal
direction. Collisions between solitons are possible due to the Galilean
invariance along the spatial axis. Outcomes of the collisions are identified by
varying the GVD coefficient, D, and the collision "velocity" (actually, it is
the spatial slope of the soliton's trajectory). At small velocities, two or
three in-phase solitons merge into a single standing one. At larger velocities,
both in-phase soliton pairs and pairs of solitons with opposite signs suffer a
transition into a delocalized chaotic state. At still larger velocities, all
collisions become quasi-elastic. A new outcome is revealed by collisions
between slow solitons with opposite signs: they self-trap into persistent
wobbling dipoles, which are found in two modifications (horizontal at smaller
D, and vertical if D is larger (the horizontal ones resemble "zigzag" bound
states of two solitons known in the 1D CGL equation of the CQ type). Collisions
between solitons with a finite mismatch between their trajectories are studied
too.
