rhbz#1283420: cairo text + xrender bodge

Change-Id: I926881bcfa4911f3d7f4899711be44a2f6d82026

vcl/unx/generic/gdi/x11cairotextrender.cxx

@@ -42,6 +42,10 @@ struct _XRegion
     BOX extents;
 };
 
+#if CAIRO_VERSION < CAIRO_VERSION_ENCODE(1, 10, 0)
+#    define CAIRO_OPERATOR_DIFFERENCE (static_cast<cairo_operator_t>(23))
+#endif
+
 X11CairoTextRender::X11CairoTextRender(X11SalGraphics& rParent)
     : mrParent(rParent)
 {
@@ -78,6 +82,20 @@ cairo_t* X11CairoTextRender::getCairoContext()
 
     cairo_t *cr = cairo_create(surface);
     cairo_surface_destroy(surface);
+
+    //rhbz#1283420 bodge to draw and undraw something which has the side effect
+    //of making the mysterious xrender related problem go away
+    if (cairo_version() >= CAIRO_VERSION_ENCODE(1, 10, 0))
+    {
+        cairo_save(cr);
+        cairo_set_source_rgb(cr, 1.0, 1.0, 1.0);
+        cairo_set_operator(cr, CAIRO_OPERATOR_DIFFERENCE);
+        cairo_rectangle(cr, 0, 0, 1, 1);
+        cairo_fill_preserve(cr);
+        cairo_fill(cr);
+        cairo_restore(cr);
+    }
+
     return cr;
 }