TideSDK is an Open Source Software stack used to develop Cross-platfrom Desktop Applications using Web-technologies like HTML, JS, CSS, etc., We have number of toolkits to develop desktop applications like GTK, QT, etc., but there are always complexities involved.
1. Download TideSDK 1.3.1 beta and extract the content to ~/.tidesdk folder.
2. Download TideSDK Developer (a kind of IDE like thing which helps you to run, launch, package your apps)
You can get started from here