Adjust preprocessor guards for Qt5/X11.

This fixes the -geometry command line option and restores the
"Use icons from system's theme" checkbox in the preferences.

There is still code addressing Qt4 and xlib that has to be
audited. This code cannot be compiled with Qt5 because the
default backend is now xcb and not xlib. I have marked such
code with a "FIXME QT5" comment.

config/qt4.m4

@@ -169,6 +169,19 @@ 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 $QT_CORE_INCLUDES"
+	  AC_EGREP_CPP(xcb,
+	    [#include <qconfig.h>
+	    QT_QPA_DEFAULT_PLATFORM_NAME],
+	    [AC_MSG_RESULT(yes)
+	     AC_DEFINE(QPA_XCB, 1, [Define if Qt uses the X Window System])],
+	    [AC_MSG_RESULT(no)])
+	  CPPFLAGS=$save_CPPFLAGS
+	fi
+
 	QT_FIND_TOOL([QT_MOC], [moc])
 	QT_FIND_TOOL([QT_UIC], [uic])
 	QT_FIND_TOOL([QT_RCC], [rcc])

src/frontends/qt4/GuiApplication.cpp

@@ -115,6 +115,7 @@
 #include <QThreadPool>
 #include <QWidget>
 
+// FIXME QT5
 #ifdef Q_WS_X11
 #include <X11/Xatom.h>
 #include <X11/Xlib.h>
@@ -167,7 +168,7 @@ namespace lyx {
 
 frontend::Application * createApplication(int & argc, char * argv[])
 {
-#ifndef Q_WS_X11
+#if !defined(Q_WS_X11) && !defined(QPA_XCB)
 	// prune -geometry argument(s) by shifting
 	// the following ones 2 places down.
 	for (int i = 0 ; i < argc ; ++i) {
@@ -1007,7 +1008,7 @@ GuiApplication::GuiApplication(int & argc, char ** argv)
     setupApplescript();
 #endif
 
-#ifdef Q_WS_X11
+#if defined(Q_WS_X11) || defined(QPA_XCB)
 	// doubleClickInterval() is 400 ms on X11 which is just too long.
 	// On Windows and Mac OS X, the operating system's value is used.
 	// On Microsoft Windows, calling this function sets the double
@@ -2948,6 +2949,7 @@ bool GuiApplication::longOperationStarted() {
 //
 // X11 specific stuff goes here...
 
+// FIXME QT5
 #ifdef Q_WS_X11
 bool GuiApplication::x11EventFilter(XEvent * xev)
 {

src/frontends/qt4/GuiApplication.h

@@ -99,6 +99,7 @@ public:
 	//@{
 	bool notify(QObject * receiver, QEvent * event);
 	void commitData(QSessionManager & sm);
+	// FIXME QT5
 #ifdef Q_WS_X11
 	bool x11EventFilter(XEvent * ev);
 #endif

src/frontends/qt4/GuiClipboard.cpp

@@ -541,7 +541,7 @@ bool GuiClipboard::hasInternal() const
 	// are notified of changes. However, on Windows ownership is
 	// emulated by Qt through the OleIsCurrentClipboard() API, while
 	// on Mac OS X we deal with this issue by ourself.
-#if defined(Q_WS_X11) || defined(Q_OS_WIN) || defined(Q_CYGWIN_WIN)
+#ifndef Q_OS_MAC
 	return true;
 #else
 	return false;

src/frontends/qt4/GuiPainter.cpp

@@ -38,7 +38,7 @@
 
 // Set USE_PIXMAP_CACHE to 1 for enabling the use of a Pixmap cache when
 // drawing text. This is especially useful for older PPC/Mac systems.
-#if defined(Q_WS_X11)
+#if defined(Q_WS_X11) || defined(QPA_XCB)
 #define USE_PIXMAP_CACHE 0
 #else
 #define USE_PIXMAP_CACHE 1

src/frontends/qt4/GuiPrefs.cpp

@@ -1046,7 +1046,7 @@ void PrefScreenFonts::updateRC(LyXRC const & rc)
 	updateScreenFontSizes(rc);
 
 	pixmapCacheCB->setChecked(rc.use_pixmap_cache);
-#if defined(Q_WS_X11)
+#if defined(Q_WS_X11) || defined(QPA_XCB)
 	pixmapCacheCB->setEnabled(false);
 #endif
 
@@ -2540,7 +2540,7 @@ PrefUserInterface::PrefUserInterface(GuiPreferences * form)
 	iconSetCO->addItem(qt_("Classic"), "classic");
 	iconSetCO->addItem(qt_("Oxygen"), "oxygen");
 
-#if (!defined Q_WS_X11 || QT_VERSION < 0x040600)
+#if (!(defined Q_WS_X11 || defined(QPA_XCB)) || QT_VERSION < 0x040600)
 	useSystemThemeIconsCB->hide();
 #endif
 }

src/frontends/qt4/GuiView.cpp

@@ -635,7 +635,7 @@ void GuiView::saveLayout() const
 	QSettings settings;
 	settings.beginGroup("views");
 	settings.beginGroup(QString::number(id_));
-#ifdef Q_WS_X11
+#if defined(Q_WS_X11) || defined(QPA_XCB)
 	settings.setValue("pos", pos());
 	settings.setValue("size", size());
 #else
@@ -679,7 +679,7 @@ bool GuiView::restoreLayout()
 	}
 	setIconSize(icon_size);
 
-#ifdef Q_WS_X11
+#if defined(Q_WS_X11) || defined(QPA_XCB)
 	QPoint pos = settings.value("pos", QPoint(50, 50)).toPoint();
 	QSize size = settings.value("size", QSize(690, 510)).toSize();
 	resize(size);

src/frontends/qt4/GuiWorkArea.cpp

@@ -695,6 +695,7 @@ void GuiWorkArea::scrollTo(int value)
 	}
 	// Show the cursor immediately after any operation.
 	startBlinkingCursor();
+	// FIXME QT5
 #ifdef Q_WS_X11
 	QApplication::syncX();
 #endif
@@ -1060,7 +1061,7 @@ void GuiWorkArea::keyPressEvent(QKeyEvent * ev)
 	// do nothing if there are other events
 	// (the auto repeated events come too fast)
 	// it looks like this is only needed on X11
-#ifdef Q_WS_X11
+#if defined(Q_WS_X11) || defined(QPA_XCB)
 	if (qApp->hasPendingEvents() && ev->isAutoRepeat()) {
 		switch (ev->key()) {
 		case Qt::Key_PageDown: