Clicking the thumbnails for image attachments (which are one of the most common types of attachment) should cause them to be shown in such a way that the issue details remain visible (in a dialog box/lightbox which can be dragged around). It is infuriating clicking on a screenshot and then having to click the Back button to figure out which issue it relates to, or having to open a new tab and find the issue again. There is not even an issue number associated with the image. The issue is about keeping the image in context with the issue details.
As a further enhancement, the dialog/lightbox could be augmented with navigation buttons to navigate between the different images attached to an issue.