  The Color Magnitude Diagram (CMD) morphology of the "extended" main sequence
turnoff (eMSTO) and upper main sequence (MS) of the intermediate age ($\lesssim
2$ Gyr) Large Magellanic Cloud Cluster NGC 1783 shows the presence of a small
group of UV-dim stars, that, in the ultraviolet Hubble Space Telescope filters,
are located at colors on the red side of the typical "fan" shape displayed by
the eMSTO. We model the UV-dim stars by assuming that some of the stars which
would intrinsically be located on the left side of the eMSTO are obscured by a
ring of dust due to grain condensation at the periphery of the excretion disc
expelled when they spin at the high rotation rates typical of stars in the Be
stage. A reasonably low optical depth at 10$\mu$ is necessary to model the
UV-dim group. Introduction of dust in the interpretation of the eMSTO may
require a substantial re-evaluation of previous conclusions concerning the role
of age and/or rotation spreads in the MC clusters: the entire eMSTO can be
populated by dusty stars, and the reddest UV-dim stars simply represents the
tail of the distribution with both maximum obscuration and the dust ring seen
along the line of sight. The model stars having higher rotational projected
velocity ($v \sin$ i) are predicted to be preferentially redder than the
slowly-rotating stars. The mass loss responsible for the dust may also cause
the non-monotonic distribution of stars in the upper main sequence, with two
peaks and gaps showing up in the UV CMD.
