<actwin> Activates specified window.  If the window doesn't exist a macro can be started (to open desired application or notify user, for example).

Command Tree:   Window  \  Activate
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Syntax:   <actwin>("WinTitle", Match, WindowState, "MacroRun")
WinTitle
Title of the window to activate.
Match
Can be one of these values:
0 - WinTitle can be substring of a window title
1 - WinTitle must exactly match a window title 
WindowState
Desired state of the window after the window is activated:
0 - Normal
1 - Minimized
2 - Maximized
3 - Let the state unchanged 
MacroRun
Name of the macro to run if the WinTitle doesn't match any existing window.  The "no" value means no macro will be run.
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Example:   <#> This macro activates "Notepad" window if it is opened
<#>
<commands_only_on>

<if_win>("Notepad","OPEN",0)
   <actwin>("Notepad",0,0,"no")
<else>
   <msg>(100,100,"'Notepad' is not opened!","Message",1)
<endif>