SumatraPDF makes it easy for you to open current document in a different program.
For example, if you also have Adobe Reader installed, you can use File menu to open PDF document you’re viewing in Adobe Reader. We auto-detect some popular apps (Adobe, Foxit, PDF X-Change etc.).
You can add custom viewers using advanced settings.
To configure an external viewer:
Relevant settings:
ExternalViewers [
  [
    CommandLine =
    Name =
    Filter =

    // ver 3.6+:
    Key = 
  ]
]
Example:
ExternalViewers [
  [
    CommandLine = "C:\Program Files\FoxitReader\FoxitReader.exe" /A page=%p "%1"
    Name = Foxit &Reader
    Filter = *.pdf
    Key = Ctrl + m
  ]
]
CommandLine is a full path of executable to open a file with arguments.
Arguments can use special values:
Please make sure to use quotes around file / directory special values (i.e. "%1" and "%d") to avoid issues with file paths that have spaces in them.
Name will be displayed in File menu.
Filter restricts which files can be opened by the reader. For example:
Key is optional and is a keyboard shortcut to invoke that viewer. Available in 3.6 and later.

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