Inside Bar EA

Please specify what you mean with an "Inside Bar EA"

I know it might seem strange, but a google of "inside Bar EA MQL4" turns up a few.

The top entry is ... WOW! this forum entry!! (YMMV)

The next one at http://www.tradingsystemforex.com certainly includes mql4 code.

I'm sure there are several people here who would be delighted to do more searching for you ... and charge you by the hour.

Sorry, I'm not so uptodate with all available indicators and strategies.

To be more specific to brewmanz informations, try this: https://www.forex-tsd.com/metatrader-4/3592-inside-bar.html

I was on the other forum, but still don't understand the use. Is it a kind of a additional bar and in which language are those mq4 extension files written?

As you are in the MQL forum for MetaTrader 4, it is written in MQL for this trading software.

To find out more about "Inside bar" please do some search via a search engine like google.