Configuring code coverage measurement
Press CtrlAlt0S to open settings and then select Build, Execution, Deployment | Coverage.
Define how the collected coverage data will be processed:
Show options before applying coverage to the editor: show the Code Coverage dialog every time you run a new run configuration with code coverage.
Do not apply collected coverage: discard the new code coverage results.
Replace active suites with the new one: discard the active suites and use the new one every time you launch a new run configuration with code coverage.
Add to the active suites: add new code coverage suites to the active suites every time you launch a new run configuration with code coverage.
Select the Activate Coverage View checkbox to open the Coverage tool window automatically.
Press CtrlAlt0S to open settings and then select Editor | Color Scheme | General.
Alternatively, click
in the popup that opens on clicking the coverage indication line in the gutter.
In the list of components, expand the Line Coverage node and select a type of coverage: for example, Full, Partial or Uncovered.
Click the Foreground field to open the Select Color dialog.
Select a color, apply the changes, and close the dialog.

Thanks for your feedback!