How do I cut pixels?

[bkorb]

1. I cut some pixels and they were replaced by the background color. Erasing didn't work either. Cutting pixels is supposed to make the next layer visible where I've cut the pixels. I had to use a mask.
2. I pasted the pixels and the pixels were empty. (I pasted and limited visibility to the anchored-to layer.)
3. I used the paintbrush (pencil) and it said it would only do white. I couldn't change it to black. Even as a white brush, I couldn't paint the white into an empty layer

Since I don't know how to change default behavior, I have no idea what is wrong. I could copy the file over to my Mac and use Photoshop, but for a quick edit of a PNG file, I'd rather just use Gimp as I've been able to do for the last couple of decades.
But not anymore.

[rich2005]

You need an alpha channel for the layer you are using. Layer -> Transparency -> Add Alpha Channel If it is greyed-out then there is already one. Also an indication in the layer name No alpha, the layer name is bold
No alpha channel, then erasing (cut) uses the BG colour. You must have had white as the BG colour.

   

If you have the latest Gimp (no guarantee with MacOS) then in Edit -> Preferences -> Image Import & Export  there is a check box for Add an alpha channel to Imported images

OH...just reread the post

Quote:3. I used the paintbrush (pencil) and it said it would only do white. I couldn't change it to black. Even as a white brush, I couldn't paint the white into an empty layer

What is the mode of the image ? Is it Indexed ? Check with Image -> Mode Set it to RGB
If you can post a screenshot of the problem, to include tool options / layer dock / anything helpful.

[bkorb]

1. I've now added "add an alpha channel to imported images." Odd that a new, crucial attribute defaults to "off."
2. On the layer I added to scribble on, the "alpha channel" was greyed out, so I guess that attribute was already there.
3. the image mode is set to RGB

On the "dots" layer, I'm trying to put a separator after the first paragraph and before the second, as you can see with the "draw a straight line" tool.

Also, I'm still curious why cut & paste isn't working. I had to accomplish it by duplicating the layers, masking, moving and merge downing. I clipped out several paragraphs between the first and second paragraphs that appear.

[rich2005]

No real useful comments except a seletion cut works fine provided I am on the appropriate layer.

From your screenshot, drawining in a line of dots using click-shift start -to-finish. The brush spacing is a percentage. set it to 200% - 300% ... 

   

[bkorb]

OK. I'm now completely convinced: there are some obscure settings that effectively disable GIMP. Is there a straight forward way to reset ~/.config/GIMP/2.10 or ~/.gimp-2.8 ? Probably, I can just blow the latter away. It looks like an old dinkleberry.

<time passes>

I renamed GIMP/2.10 out of the way and restarted GIMP. I get the same behavior. Benefit of new directory: all the tool windows are once again attached to the main window. Sadly, I did click on the brush attributes a few times and GIMP decided that that meant I wanted to detach the brush attributes window. I did not. I also don't know how to put it back. Dragging the window into the tool bar of the main window normally does stuff like that. Nope. I've just been putting up with it rather than chasing down exactly how to fix it. -- I got used to the way Chrome and Photoshop work, just grabbing the menu bar instead of the folder tab under the menu bar. "Never mind."

Anyway, I tried to screen grab your line of dots to paste into my doc -- no go. If you look at the feint selection on the paste layer, you see there are no data there. Consequently, "merge down" is disabled. I can't show you that because when the menu is active, the screen capture is disabled. "Clever." I guess I do need to go back and re-enable that alpha thingy.

So, I have a brand new GIMP/2.10 directory that is presumably populated with the defaults and GIMP is still non-functional.

[rich2005]

Quote:..So, I have a brand new GIMP/2.10 directory that is presumably populated with the defaults and GIMP is still non-functional.

Really ?

It might just be your old way of processing especially if (from first post) "I could copy the file over to my Mac and use Photoshop"

No idea of why things not going your way.

Have a look at this https://youtu.be/2ViunLH8ZyA only a couple of minutes. Does anything apply to your problem

[bkorb]

I watched the video and, to the best of my knowledge, it's exactly what I do. (Aside from trying to paint outside of a selected area or copying from an empty layer. _Those_ I do know to avoid.) I finally opened the screen grab of your dots as layers above the text. So I got what I needed, but it was not the easiest way to do it. When I did the copy/paste above, I had opened the screen grab as a separate window, selected "all" and copied to the clipboard. When I pasted, I got what you see above: an empty paste layer with the marching ants in the upper left outlining what ought to have been a copy of your dots.

Also, to be completely clear, I have done this copy/delete/paste/merge stuff many times before without issue. Maybe next time I'll do a complete uninstall/reinstall cycle to be 100% certain that no residual state is interfering.

FYI: https://twitter.com/bruckorb/status/1397971273360105472