Summary:
When viewing the logs for an individual stage in stage view (by clicking on that stage and selecting "Logs"), the user is not able to copy content from those logs into their clipboard, because the highlighted area gets deselected as soon as they release the mouse button.

Steps to recreate:
1. Create a very simple pipeline. Mine looks like:

node {
    currentDirectory = pwd()

    stage ("thing") {
        sh "echo HERE IT IS ${currentDirectory}"
        echo "PWD is ${currentDirectory}"
    }
}

2. Run the pipeline.

3. Click in the green "stage' area of any existing run, and click Logs:

4. Pick an entry in the popover.

5. Click and hold the left mouse button to select some text. That behaves normally.

6. But the moment you release your mouse button, the "selection' disappears. Makes it very difficult to copy something into the clipboard for later use, like for a Google search.

I can try to get a video captured if that would help.