GIMP Version: 2.10.12
Operating System: Windows
OS Version: Win 10 Pro
GIMP Experience: New User

List any relevant plug-ins or scripts:
None

List any ERROR messages you received:
None

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I am using Quickmask to clean up a selection. I do this by creating a selection within QM using Rectangular Select and positioning it as desired. I then select the Paint Bucket tool and click within this selection, which either adds to or subtracts from the selection, depending on the foreground color.

I occasionally save the entire selection by getting out of QM and clicking on Select > Selection to Channel. I do this so that if I screw up, I can go back to this selection, and all my selection work is not lost.

Occasionally, with QM open, when I click in the small selection, it paints this selection white (FG color) rather than changing the selection as is normal.

Can anyone tell me what I'm doing wrong and how to prevent this.

Thanks for any help you can give me.

Ray

I have seen this, too. Not so much painting with some color, as in your case, but similar things happen. Not sure about the cause, but I suspect it may have something to do with GIMP losing focus to the image window where the painting takes place.

I usually see this when I have switched to something else and then go back to GIMP, or I've done something in some menu or some other dialog, say accidentally going into the Layers dialog or something. For me, switching out of QuickMask mode (Shift-Q) and then switch it on again, seems to work.

Since I turned on focus following the mouse pointer on my Linux system this happens less often, but depending on which system you use, this might not be an option for you.

I seem to recall some Explorer add-on for Windows when I used that system some oh, 15 years ago or something, I think it was XP back then. There was some thing you could download and install to get this or a similar behavior.

That has happened to me in the past

It is probably the layer you are working on set as active.

When QM is toggled, the layer becomes inactive and the QM channel is active. Toggle QM off and layer is active again.

Make a Channel from Selection and the layer again becomes inactive. If QM is toggled and you move back to layers and make the layer active, then you paint in the layer not the QM.

Demo of that sequence. https://i.imgur.com/De9jXp1.mp4