Since I've been using an android phone lately much of my calendar and mail stuff is on google services, so naturally I wanted to sync my calendar, contacts, and mail with google. Fortunately this is all possible, unfortunately it's not all that clear how to set it up. So here's a quick walkthrough for future reference.
Lets look at the tricky one, calendars. To add a google calendar to your korganizer you just need the caldav address which you can get from the calendar's settings like this.
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Then you'll need the google calendar url to plug your calendar's address into which can be found in the help section, here for convenience:
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Then you can open korganizer (or kontact) and right click the calendar manager and choose Add Calendar. It will give you a list of resources like this:
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Since google calendars support CalDav choose the Dav groupware resource. Here's where the ui could use some update and/or simplification. The next thing you will see is a list of calendar providers, of which google is not a part like this:
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You can finally put in your url (combine the google calendar url with your calendar's address) and enter your username (foo@gmail.com) and hit the fetch button. After entering your username again (not sure why it doesn't take the one you already set) and password you are able to choose your calendar and add it to korganizer.
Anyone that votes we simplify this process raise your hand :) o/