You can control SumatraPDF with DDE commands.
They are mostly used to use SumatraPDF as a preview tool from e.g. LaTeX editors that generate PDF files.
Single DDE command:
[Command(parameter1, parameter2, ..., )]
Multiple DDE commands:
[Command1(parameter1, parameter2, ..., )][Command2(...)][...]
Since 3.5 (currently in pre-release) you can send all named commands.
newwindowis 1 then a new window is created even if the file is already open
focusis 1 then the focus is set to the window
forcerefreshis 1 the command forces the refresh of the file window if already open (useful for files opened over network that don't get file-change notifications)".
[Open("c:\\file.pdf", 1, 1, 0)]
pdffilepath: path to the PDF document (if this path is omitted and the document isn't already open, SumatraPDF won't open it for you)
column: this parameter is for future use (just always pass 0)
newwindow: 1 to open the document in a new window (even if the file is already opened)
focus: 1 to set focus to SumatraPDF's window.