Revert "require at least gtk3 3.20.0 to build and run gtk3 bits"

Linux-deb-x86_64_56-lhm-ubuntu-trusty is at 3.18, not defunct
Linux-Ubuntu-x86_64_54-TDE

This reverts commit 75e828cad5.

Change-Id: I8939e4bb1876186f5ed75b3ad4c2626e37e4c81c

vcl/inc/unx/gtk/gtkgdi.hxx

@@ -131,7 +131,9 @@ public:
 
     virtual void GetResolution(sal_Int32& rDPIX, sal_Int32& rDPIY) override;
 
-    GtkStyleContext* createStyleContext(GtkControlPart ePart);
+    GtkStyleContext* createStyleContext(gtk_widget_path_iter_set_object_nameFunc set_object_name, GtkControlPart ePart);
+    GtkStyleContext* createNewContext(GtkControlPart ePart, gtk_widget_path_iter_set_object_nameFunc set_object_name);
+    GtkStyleContext* createOldContext(GtkControlPart ePart);
     GtkStyleContext* makeContext(GtkWidgetPath *pPath, GtkStyleContext *pParent);
 private:
     GtkWidget       *mpWindow;

vcl/unx/gtk/gtkinst.cxx

@@ -82,7 +82,7 @@ extern "C"
             XInitThreads();
 
 #if GTK_CHECK_VERSION(3,0,0)
-        if (gtk_minor_version < 20)
+        if (gtk_minor_version < 18)
         {
             g_warning("require a newer gtk than 3.%d for theme expectations", gtk_minor_version);
             return nullptr;

vcl/unx/gtk/gtksalmenu.cxx

@@ -630,7 +630,12 @@ void GtkSalMenu::ShowCloseButton(bool bShow)
       "min-width: 18px;"
       "min-height: 18px;"
       "}";
-    gtk_css_provider_load_from_data(pProvider, data, -1, nullptr);
+    const gchar olddata[] = "* { "
+      "padding: 0;"
+      "margin-left: 8px;"
+      "margin-right: 8px;"
+      "}";
+    gtk_css_provider_load_from_data(pProvider, gtk_check_version(3, 20, 0) == nullptr ? data : olddata, -1, nullptr);
     gtk_style_context_add_provider(pButtonContext,
                                    GTK_STYLE_PROVIDER(pProvider),
                                    GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);

vcl/unx/gtk3/gtk3gtkframe.cxx

@@ -2081,15 +2081,36 @@ void GtkSalFrame::grabPointer( bool bGrab, bool bOwnerEvents )
     if (!m_pWindow)
         return;
 
-    GdkSeat* pSeat = gdk_display_get_default_seat(getGdkDisplay());
+#if GTK_CHECK_VERSION(3, 20, 0)
+    if (gtk_check_version(3, 20, 0) == nullptr)
+    {
+        GdkSeat* pSeat = gdk_display_get_default_seat(getGdkDisplay());
+        if (bGrab)
+        {
+            gdk_seat_grab(pSeat, widget_get_window(getMouseEventWidget()), GDK_SEAT_CAPABILITY_ALL_POINTING,
+                          bOwnerEvents, nullptr, nullptr, nullptr, nullptr);
+        }
+        else
+        {
+            gdk_seat_ungrab(pSeat);
+        }
+        return;
+    }
+#endif
+
+    //else older gtk3
+    const int nMask = (GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK | GDK_POINTER_MOTION_MASK | GDK_POINTER_MOTION_HINT_MASK);
+
+    GdkDeviceManager* pDeviceManager = gdk_display_get_device_manager(getGdkDisplay());
+    GdkDevice* pPointer = gdk_device_manager_get_client_pointer(pDeviceManager);
     if (bGrab)
     {
-        gdk_seat_grab(pSeat, widget_get_window(getMouseEventWidget()), GDK_SEAT_CAPABILITY_ALL_POINTING,
-                      bOwnerEvents, nullptr, nullptr, nullptr, nullptr);
+        gdk_device_grab(pPointer, widget_get_window(getMouseEventWidget()), GDK_OWNERSHIP_NONE,
+                        bOwnerEvents, (GdkEventMask) nMask, m_pCurrentCursor, gtk_get_current_event_time());
     }
     else
     {
-        gdk_seat_ungrab(pSeat);
+        gdk_device_ungrab(pPointer, gtk_get_current_event_time());
     }
 }