Add Transparent Window to Existing

[DestructZero]

I've searched all over and I can't seem to find the answer to my question. I have a PNG image of an airplane fuselage with two windows that are transparent. All I want to do is to add a third window between them, and I can't make it work. I've read that I need to create a new layer and 'Add Alpha Channel' but that option is greyed out. I also read that if I do Windows --> Dockable Dialogs --> Channels and see 'Alpha' as an option (which is there) that means the Alpha Channel has already been added, which I guess makes sense because there are already two 'windows' on the image that are transparent.

With that information, could someone please walk me through the steps to create a third window that will be transparent? The online videos and help I've found show me how to remove the background around a part of an image to make it transparent, but that's not what I need in this case.

Thank you very much for your help!

[Krikor]

(07-13-2024, 04:12 PM)DestructZero Wrote: I've searched all over and I can't seem to find the answer to my question. I have a PNG image of an airplane fuselage with two windows that are transparent. All I want to do is to add a third window between them, and I can't make it work. I've read that I need to create a new layer and 'Add Alpha Channel' but that option is greyed out. I also read that if I do Windows --> Dockable Dialogs --> Channels and see 'Alpha' as an option (which is there) that means the Alpha Channel has already been added, which I guess makes sense because there are already two 'windows' on the image that are transparent.

With that information, could someone please walk me through the steps to create a third window that will be transparent? The online videos and help I've found show me how to remove the background around a part of an image to make it transparent, but that's not what I need in this case.

Thank you very much for your help!

Without an image as an example I am left with assumptions.
What I could suggest with the idea I have in mind about the situation is that you could use ready-made images like those found for example at: https://www.freepik.com/free-photos-vect...ransparent
Another option would be to use the Clone Tool and copy one of the windows to create the third. 

[denzjos]

Do you want full transparent or half transparent. Full is just select an area and delete the selection. Half is by copy the selection to a new layer and delete the selection on the plane. Then make the new layer half transparent so you can see the background (here faces in the example)  
   

[rich2005]

It is better if you post the image or if greater than 500kb a link to the image.

Some pointers. 
When a layer has an alpha channel, transparency, the layer name is normal type. No transparency, the layer name is in bold type. (3)

A different check is Layer -> Transparency -> Add Alpha Channel. When that is "greyed-out" the layer already has transparency.

Then it depends on your image. Not all downloads are truthful. Transparency is usually denoted in graphics as a checker pattern. Sometimes that pattern is "baked-into" the image (1). That is not transparency. Transparency in Gimp will show solid underlying layers (2)