FreeFileSync opens the operating system's standard file browser per default on each double-click e.g. by invoking "explorer /select, %name" on Windows.
If some other application shall be started instead, just navigate to "Menu -> Advanced -> Global settings: External Applications" and add or replace a command string. The first one is used when double-clicking while all subsequent entries are still available in right-click context menu on main dialog. The following macros are available:
%name - full
file or directory name
%dir - directory part
only
%nameCo - Other side's counterpart to %name
%dirCo -
Other side's counterpart to %dir
Example:
Start associated application: cmd /c start "" "%name"
Start visual difference tool: C:\Program Files\WinMerge\WinMergeU.exe "%name" "%nameCo"
Note:
Don't forget to use
quotation marks if file names contain spaces!