I am a new user of SumatraPDF and want to customize its appearance and integrate an external viewer. Please provide details on how to customize the UI colors/theme and how to set up an external viewer. Additionally, I want to report a bug; what is the recommended way to submit a bug report?
Navigate to 'https://www.sumatrapdfreader.org/manual'. Click on the 'Customizing UI colors / theme' link. Extract information on how to customize UI colors/theme. Go back to the 'Manual' page. Click on the 'Customize external viewers' link. Extract information on how to customize external viewers. Go back to the 'Manual' page. Locate and click on the 'How to submit bug reports' link. Extract information on the recommended way to submit bug reports. Synthesize all gathered information into a concise answer.
The agent successfully navigates to the 'Customizing UI colors / theme' section and explains how to do so (e.g., by editing `Advanced Settings.txt`). The agent successfully navigates to the 'Customize external viewers' section and explains how to do so (e.g., by editing `Advanced Settings.txt` and specifying the command line for the external viewer). The agent successfully navigates to the 'How to submit bug reports' section and states that bug reports should be submitted via the issue tracker on GitHub.