9.37.3 Can you answer these questions?

9.37.3.1 How to search for content in all my Mathematica files, or in the opened ones?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=292036

I have one file where I used the package 'ReactionKinetics' but I forgot where. Does Mathematica allow for searches in all  Mathematica files, or in the opened ones, like certain editors (Winedt, ...) ... 
[searching]
 

asked by florin https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=54979 Score of 1

9.37.3.2 Changing cell selection style

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=292008

How to change this default selection style for a cell? 
[cells] [style]
                                                                                  

                                                                                  
 

asked by swish https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=2490 Score of 1

9.37.3.3 Symbolic integral with UnitStep functions

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=292034

I want to symbolically evaluate the following integral (with real positive parameters  L1 ,  L2 , ... 
[calculus-and-analysis] [symbolic]
 

asked by Giancarlo Creanza https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=92613 Score of 2