Mass add source files
The Solution Editor supports the multi-selection of files that can be added simultaneously.
All source files in the Piwik demo project have filename en.json.
Open the Search dropdown. It provides some prepared search functions.

If you select
Resx files, then after the selection, the Search box will show\.resx$.
This is a Regular Expression that selects all files that end with
.resx(for details, see the 'Regular expression' article on Wikipedia). The $ indicates the end-of-string.Enter the regular expression in the Search field.
For the demo application Piwik, we want to select all files with the name
en.json. Note that the regular expression needs to escape the dot.
Click the Apply button. All files with the name
en.jsonhave been selected.
Right-click one of the selected files to see the context menu.
Select the Include in Project option. All files are added to the project, and a file overview is displayed.

If needed, change the Target rule and Parser for all selected files. The files are then added to the project.