The users of BlackBerry 10 wanted a bit more control on their device and they demanded a choice for choosing a dark or light theme for calendar and contacts app. BlackBerry always care about the BlackBerry users and it is said that this option will be available in the OS 10.2. The OS 10.2 is not yet announced and you have to wait for its release. But if you want the option of choosing Dark or Light theme right now in your Blackberry 10 we have a way. You can sideload it on your BlackBerry 10. You can download the bar files from the following link http://goo.gl/zzCFjB. Once installed you can have the option to choose between the dark and light theme in calendar and contacts of BlackBerry 10.
You can see the option to choose between dark and light theme in the screen shot above. You can choose between the Dark and Light theme.To apply the theme you must exit the contacts or calendar and relaunch the app.
Disclaimer: (Please side load the app on your own risk we don’t responsibility for any loss done to your device during or after side loading.)