Why does the layer row become red when I enter Quick Mask?

Thanks a lot for this link Joseph, addresses a lot of issues I'm having, like how to copy a mask from one layer to another (without loading it to a selection and then saving the selection as a mask, which was the only way I could figure out so far).

OK, thanks for your help, I'll try that.

Something's got to be wrong, because although I am expecting to be in quick mask mode (I just pressed Q, and the history also says "entered quick mask") the cursor on the image is not a brush, but the cursor of the move tool.

And I am not able to mask.

If I press Q again, history says that I am leaving quick mask, and I still have the cursor of the move tool.

Basically typing Q turns this layer red in the layer panel and creates a new line in the history, but other than that has no effect.

Any idea ?

Note: I had tried to create a mask based on color range earlier, and this mask got saved as a new Channel. The channel mask has the little eye on to indicate visibility, while the RGB eyes are not on.

As Dave mentioned above, there is nothing wrong here; it simply indicates you've entered the Quick Mask mode.  You can alter the color by clicking on Select and Mask... after making a e selection and choose a different color, which will both alter the color of the actual mask and overlay color in the layers palette.