Fix paste of selection to (unfocused) external applications

With both Qt4 and Qt5, when using a click-to-focus policy, the first
attempt to paste a selection by middle mouse in an external application
which has no focus may fail. It is not clear why this succeeds for some
applications and fails for others, but refreshing the timestamp of the
selection request cures the issue. The cmake part is by Kornel.

See also this thread:
http://thread.gmane.org/gmane.editors.lyx.devel/162491

CMakeLists.txt

@@ -925,11 +925,6 @@ endif()
 include(${LYX_CMAKE_DIR}/ConfigureChecks.cmake)
 configure_file(${LYX_CMAKE_DIR}/configCompiler.h.cmake ${TOP_BINARY_DIR}/configCompiler.h)
 
-set(QPA_XCB)
-if(Qt5X11Extras_FOUND AND QT_USES_X11)
-  # QPA_XCB is only valid if QT5+X11
-  set(QPA_XCB 1)
-endif()
 configure_file(${LYX_CMAKE_DIR}/config.h.cmake ${TOP_BINARY_DIR}/config.h)
 
 if(QTVERSION MATCHES "^([0-9]+)\\.([0-9]+)\\.([0-9]+).*")

config/qt4.m4

@@ -172,18 +172,30 @@ AC_DEFUN([QT_DO_IT_ALL],
 	[AC_MSG_ERROR([LyX requires at least version $1 of Qt. Only version $QTLIB_VERSION has been found.])
 	])
 
-	if test x$USE_QT5 = xyes ; then
 	save_CPPFLAGS=$CPPFLAGS
 	AC_MSG_CHECKING([whether Qt uses the X Window system])
 	CPPFLAGS="$save_CPPFLAGS $QT_CORE_INCLUDES"
+	if test x$USE_QT5 = xyes ; then
 	  AC_EGREP_CPP(xcb,
 	    [#include <qconfig.h>
 	    QT_QPA_DEFAULT_PLATFORM_NAME],
 	    [AC_MSG_RESULT(yes)
 	     AC_DEFINE(QPA_XCB, 1, [Define if Qt uses the X Window System])],
 	    [AC_MSG_RESULT(no)])
-	  CPPFLAGS=$save_CPPFLAGS
+	else
+	  AC_PREPROC_IFELSE([AC_LANG_SOURCE([
+	    [#include <qglobal.h>],
+	    [#ifndef Q_WS_X11],
+	    [#error Fail],
+	    [#endif]])],
+	    qt_use_x11=yes,
+	    qt_use_x11=no)
+	  AC_MSG_RESULT($qt_use_x11)
+	  if test "x$qt_use_x11" = "xyes"; then
+	    QT_LIB="$QT_LIB -lX11"
 	  fi
+	fi
+	CPPFLAGS=$save_CPPFLAGS
 
 	QT_FIND_TOOL([QT_MOC], [moc])
 	QT_FIND_TOOL([QT_UIC], [uic])
@@ -209,6 +221,13 @@ AC_DEFUN([QT_DO_PKG_CONFIG],
 	if test "x$USE_QT5" != "xno" ; then
 		qt_corelibs="Qt5Core"
 		qt_guilibs="Qt5Core Qt5Concurrent Qt5Gui Qt5Svg Qt5Widgets"
+		lyx_use_x11extras=false
+		PKG_CHECK_EXISTS(Qt5X11Extras, [lyx_use_x11extras=true], [])
+		if $lyx_use_x11extras; then
+			qt_guilibs="$qt_guilibs Qt5X11Extras xcb"
+			AC_DEFINE(HAVE_QT5_X11_EXTRAS, 1,
+				[Define if you have the Qt5X11Extras module])
+		fi
 		lyx_use_winextras=false
 		PKG_CHECK_EXISTS(Qt5WinExtras, [lyx_use_winextras=true], [])
 		if $lyx_use_winextras; then

development/cmake/ConfigureChecks.cmake

@@ -12,6 +12,7 @@ include(CheckFunctionExists)
 include(CheckLibraryExists)
 include(CheckTypeSize)
 include(CheckCXXSourceCompiles)
+include(CheckCXXSourceRuns)
 include(MacroBoolTo01)
 include(TestBigEndian)
 
@@ -197,7 +198,30 @@ else()
   endif()
 endif()
 
+set(QPA_XCB)
+set(HAVE_QT5_X11_EXTRAS)
 if(LYX_USE_QT MATCHES "QT5")
+
+  set(CMAKE_REQUIRED_INCLUDES ${Qt5Core_INCLUDE_DIRS})
+  set(CMAKE_REQUIRED_FLAGS)
+  #message(STATUS "Qt5Core_INCLUDE_DIRS = ${Qt5Core_INCLUDE_DIRS}")
+  check_cxx_source_runs(
+    "
+    #include <QtCore/qconfig.h>
+    #include <string>
+    using namespace std;
+    string a(QT_QPA_DEFAULT_PLATFORM_NAME);
+    int main(int argc, char **argv)
+    {
+      if (a.compare(\"xcb\") == 0)
+	return(0);
+      else
+	return 1;
+    }
+    "
+    QT_USES_X11)
+  set(QPA_XCB ${QT_USES_X11})
+
   if (Qt5X11Extras_FOUND)
     get_target_property(_x11extra_prop Qt5::X11Extras IMPORTED_CONFIGURATIONS)
     get_target_property(_x11extra_link_libraries Qt5::X11Extras IMPORTED_LOCATION_${_x11extra_prop})
@@ -215,7 +239,8 @@ if(LYX_USE_QT MATCHES "QT5")
               bool isX11 = QX11Info::isPlatformX11();
             }
             "
-    QT_USES_X11)
+      QT_HAS_X11_EXTRAS)
+    set(HAVE_QT5_X11_EXTRAS ${QT_HAS_X11_EXTRAS})
   endif()
   if (Qt5WinExtras_FOUND)
     get_target_property(_winextra_prop Qt5::WinExtras IMPORTED_CONFIGURATIONS)

src/frontends/qt4/GuiApplication.cpp

@@ -121,10 +121,14 @@
 #ifdef Q_WS_X11
 #include <X11/Xatom.h>
 #include <X11/Xlib.h>
+#include <QX11Info>
 #undef CursorShape
 #undef None
 #elif defined(QPA_XCB)
 #include <xcb/xcb.h>
+#ifdef HAVE_QT5_X11_EXTRAS
+#include <QtX11Extras/QX11Info>
+#endif
 #endif
 
 #if (QT_VERSION < 0x050000) || (QT_VERSION >= 0x050400)
@@ -3130,8 +3134,26 @@ bool GuiApplication::x11EventFilter(XEvent * xev)
 		BufferView * bv = current_view_->currentBufferView();
 		if (bv) {
 			docstring const sel = bv->requestSelection();
-			if (!sel.empty())
+			if (!sel.empty()) {
 				d->selection_.put(sel);
+				// Refresh the selection request timestamp.
+				// We have to do this by ourselves as Qt seems
+				// not doing that, maybe because of our
+				// "persistent selection" implementation
+				// (see comments in GuiSelection.cpp).
+				XSelectionEvent nev;
+				nev.type = SelectionNotify;
+				nev.display = xev->xselectionrequest.display;
+				nev.requestor = xev->xselectionrequest.requestor;
+				nev.selection = xev->xselectionrequest.selection;
+				nev.target = xev->xselectionrequest.target;
+				nev.property = 0L; // None
+				nev.time = CurrentTime;
+				XSendEvent(QX11Info::display(),
+					nev.requestor, False, 0,
+					reinterpret_cast<XEvent *>(&nev));
+				return true;
+			}
 		}
 		break;
 	}
@@ -3166,8 +3188,29 @@ bool GuiApplication::nativeEventFilter(const QByteArray & eventType,
 		BufferView * bv = current_view_->currentBufferView();
 		if (bv) {
 			docstring const sel = bv->requestSelection();
-			if (!sel.empty())
+			if (!sel.empty()) {
 				d->selection_.put(sel);
+#ifdef HAVE_QT5_X11_EXTRAS
+				// Refresh the selection request timestamp.
+				// We have to do this by ourselves as Qt seems
+				// not doing that, maybe because of our
+				// "persistent selection" implementation
+				// (see comments in GuiSelection.cpp).
+				xcb_selection_notify_event_t nev;
+				nev.response_type = XCB_SELECTION_NOTIFY;
+				nev.requestor = srev->requestor;
+				nev.selection = srev->selection;
+				nev.target = srev->target;
+				nev.property = XCB_NONE;
+				nev.time = XCB_CURRENT_TIME;
+				xcb_connection_t * con = QX11Info::connection();
+				xcb_send_event(con, 0, srev->requestor,
+					XCB_EVENT_MASK_NO_EVENT,
+					reinterpret_cast<char const *>(&nev));
+				xcb_flush(con);
+#endif
+				return true;
+			}
 		}
 		break;
 	}