This is obscure.

My colour sampler (Alt + Click) stopped working yesterday afternoon.

Thinking back afterwards, I realised that I had been experimenting with the Colour Samples features (where we keep a storage chest of colour samples) and it was after this that the colour sampler (where we pick colours from the canvas) had stopped working.

This morning I tried again. The colour sampler worked, but then when I used the Colour Samples pod the colour sampler again stopped functioning.

I restarted ArtRage and everything worked perfectly. I couldn't reproduce the condition. Colour Samples and Colour Sampler worked in perfect harmony.

I offer this up for what it's worth.

Oh, I'll just check if 5.0.2 is available yet.

Keep smiling ...