New LFUN lyx-activate to focus LyX window

On Linux and Mac OS, this action brings the LyX window into focus.
Such behavior is not allowed by Windows OS so instead the color of
the taskbar entry is changed to indicate that the window has changed
in some way.

The action is hidden in the shortcuts menu because it would make
sense to assign a shortcut to it. The only way to execute shortcut
would be if the LyX window is already activated.

lyx-activate will be used (see next commit) to allow the PDF viewer
to switch to LyX after executing a reverse search.

lib/RELEASE-NOTES

@@ -22,6 +22,9 @@ material in different versions easier.
 * branch-invert
   Toggles inversion status of branch inset.
 
+* lyx-activate
+  Activates the LyX window. Useful in combination with reverse search.
+
 
 !!!The following LyX functions have been changed in 2.3:
 

lib/doc/LFUNs.lyx

@@ -7025,6 +7025,26 @@ This is probably usable only with connection to lyxserver.
 Syntax command-prefix
 \end_layout
 
+\begin_layout Subsection*
+lyx-activate
+\end_layout
+
+\begin_layout Description
+Action Activates the LyX window.
+\end_layout
+
+\begin_layout Description
+Notion On Linux and Mac OS, this action brings the LyX window into focus. Such behavior is not allowed by Windows OS so instead the color of the taskbar entry is changed to indicate that the window has changed in some way. This action is useful in combination with reverse search.
+\end_layout
+
+\begin_layout Description
+Syntax lyx-activate
+\end_layout
+
+\begin_layout Description
+Origin skostysh, 4 Aug 2016
+\end_layout
+
 \begin_layout Subsection*
 self-insert
 \end_layout

src/FuncCode.h

@@ -466,6 +466,7 @@ enum FuncCode
 	LFUN_BUFFER_MOVE_PREVIOUS,      // skostysh 20150408
 	LFUN_TABULAR_FEATURE,           // gm, 20151210
 	LFUN_BRANCH_INVERT,             // rgheck, 20160712
+	LFUN_LYX_ACTIVATE,              // skostysh, 20160804
 	LFUN_LASTACTION                 // end of the table
 };
 

src/LyXAction.cpp

@@ -2715,6 +2715,19 @@ void LyXAction::init()
  * \endvar
  */
 		{ LFUN_LYX_QUIT, "lyx-quit", NoBuffer, Buffer },
+/*!
+ * \var lyx::FuncCode lyx::LFUN_LYX_ACTIVATE
+ * \li Action: Activates the LyX window.
+ * \li Notion: On Linux and Mac OS, this action brings the LyX window
+               into focus. Such behavior is not allowed by Windows OS
+               so instead the color of the taskbar entry is changed to
+               indicate that the window has changed in some way.
+               This action is useful in combination with reverse search.
+ * \li Syntax: lyx-activate
+ * \li Origin: skostysh, 4 Aug 2016
+ * \endvar
+ */
+		{ LFUN_LYX_ACTIVATE, "lyx-activate", ReadOnly | NoBuffer, Hidden },
 /*!
  * \var lyx::FuncCode lyx::LFUN_TOOLBAR_TOGGLE
  * \li Action: Toggles visibility of a given toolbar between on/off/auto.

src/frontends/qt4/GuiView.cpp

@@ -2055,6 +2055,7 @@ bool GuiView::getStatus(FuncRequest const & cmd, FuncStatus & flag)
 		break;
 
 	case LFUN_SERVER_GOTO_FILE_ROW:
+	case LFUN_LYX_ACTIVATE:
 		break;
 	case LFUN_FORWARD_SEARCH:
 		enable = !(lyxrc.forward_search_dvi.empty() && lyxrc.forward_search_pdf.empty());
@@ -3978,6 +3979,10 @@ void GuiView::dispatch(FuncRequest const & cmd, DispatchResult & dr)
 			goToFileRow(to_utf8(cmd.argument()));
 			break;
 
+		case LFUN_LYX_ACTIVATE:
+			activateWindow();
+			break;
+
 		case LFUN_FORWARD_SEARCH: {
 		// it seems safe to assume we have a document buffer, since
 		// getStatus wants one.