On Windows at least, you can drag&drop a file (like from File Explorer) onto the IDE's editor tab bar. The icon should show "Link"; when you release, it will open in a new tab.
If you hover over a tab, it will show the full path to the file. So if you used Go To Definition to open a .h, that will help you file related files. In some rare cases, GTD opens the .cpp; haven't figured out why.