It's an extension of Selenium IDE. See http://selite.github.io/ and http://selite.github.io/Components.
It makes Selenium IDE accept HTML from native clipboard, regardless of its souce (potentially another Selenium IDE instance, or a file), as far as it fits the format.
It allows Selenese commands to be indented (prefixed by spaces): that is beneficial for structured commands that come with SeLite SelBlocks Global. You can add or change indentation of existing scripts through menu or by pressing right or left arrow.
When you use structured commands (that come with SeLite SelBlocks Global), it automatically indents commands between opening and closing structural statements. It also automatically unindents the closing statement (unless you give it some specific indentation).
You can configure auto-indentation step (which defaults to four spaces). See http://selite.github.io/Components.
Indenting logs, comments stored in cells
For details see http://selite.github.io/SeleniumIDEtips#clipboard-and-indent.
This is fully forward compatible when migrating existing Selenium IDE scripts. However, it's not backward compatible: If you save test cases with indented Selenese commands as HTML, then you uninstall SeLite Clipboard And Indent, you can still open and run them in Selenium IDE, but it won't re-save them properly: any indented commands will be lost. That is a known defect in Selenium IDE - please add a comment so that they get it fixed.
Don't report any issues here (through Mozilla). Use http://selite.github.io/TroubleShooting.
Get more value
You may benefit from other components of SeLite family. It
- improves Selenium IDE,
- enables reuse,
- supports reporting and interaction,
- facilitates team work.
Please, give moral support. Vote for third party issues. Only then SeLite can progress faster.