GIMP Problems and Tips
If you cut and paste a selection in GIMP, then it creates a new Pasted Layer containing what it refers to as a Floating Selection:
Until you deal with this "Floating Selection", GIMP will not allow you to switch to another layer or perform any further image manipulation
Until you deal with this "Floating Selection", GIMP will not allow you to switch to another layer or perform any further image manipulation. There are two ways to deal with this:
EITHER Anchor the layer which merges the pasted section down into the layer below. This is done using CTRL+H or:
Layer → Anchor:
OR create the pasted selection in it's own layer (-which is what Adobe Photoshop does by default) by clicking on the "New Layer" icon:
This should result in a new layer on top of the layer stack, containing the pasted selection:
Personally, we would always use option 2, as that gives you much more scope for adjusting things later (-as the business of image manipulation never runs as smooth as we imagine it, in our experience).
If you find that, having picked a colour from the foreground swatch, GIMP fails to paint in that colour, check the following things:
Check that you not selected a subset of the image : use CTRL+A to select the whole image
Check that the image mode is set to "RGB" using:
Image → Mode:
There is a clue in the window header as to the image mode selected. The example below shows the image is in "Indexed" mode:
In indexed mode, GIMP will only paint in one of the existing colours within the image (-presumably, this is a compression feature, to reduce the size of the image file).
GIMP 2.8 allows you to download and install various themes, which customise the look and feel of your editing sessions. See the video tutorial from Billy Kerr entitled Tutorial: Get 15 New Themes for GIMP 2.8 on Windows for more details on how to do this.