launching help viewer

Under *nix systems, if we can't find the direct location of docview, we
try the 'which docview' command. If we get a positive response, we know
docview is in the system path, and we can go ahead and launch it.

At least this doesn't instantly throw an exception when docview can't
be found on the first attempt.

1 files changed, 13 insertions, 0 deletions

diff --git a/src/corelib/x11/fpg_x11.pas b/src/corelib/x11/fpg_x11.pas
index 20974dfe..37b2b469 100644
--- a/src/corelib/x11/fpg_x11.pas
+++ b/src/corelib/x11/fpg_x11.pas
@@ -322,6 +322,7 @@ type
     function    DoGetFontFaceList: TStringList; override;
     procedure   DoWaitWindowMessage(atimeoutms: integer); override;
     function    MessagesPending: boolean; override;
+    function    GetHelpViewer: TfpgString; override;
   public
     constructor Create(const AParams: string); override;
     destructor  Destroy; override;
@@ -420,6 +421,7 @@ implementation
 
 uses
   baseunix,
+  unix,
   {$IFDEF LINUX}
   users,  { For Linux user and group name support. FPC only supports this in Linux. }
   {$ENDIF}
@@ -430,6 +432,7 @@ uses
   fpg_utils,
   fpg_form,         // for modal event support
   fpg_cmdlineparams,
+  fpg_constants,
   cursorfont,
   xatom,            // used for XA_WM_NAME
   keysym,
@@ -1433,6 +1436,16 @@ begin
   fpgCheckTimers;
 end;
 
+function TfpgX11Application.GetHelpViewer: TfpgString;
+begin
+  Result := inherited GetHelpViewer;
+  if not fpgFileExists(Result) then
+  begin
+    if fpsystem('which ' + FPG_HELPVIEWER) = 0 then
+      Result := FPG_HELPVIEWER;
+  end;
+end;
+
 function GetParentWindow(wh: TfpgWinHandle; var pw, rw: TfpgWinHandle): boolean;
 var
   rootw: TfpgWinHandle;