- fixed memory leak caused by not freeing PangoLayout objects

diff --git a/src/lingot-mainframe.c b/src/lingot-mainframe.c
index 39c13d4..5fcfdad 100644
--- a/src/lingot-mainframe.c
+++ b/src/lingot-mainframe.c
@@ -616,6 +616,7 @@ void lingot_mainframe_draw_spectrum(LingotMainFrame* frame) {
 		pango_layout_set_font_description(layout, spectrum_legend_font_desc);
 		gdk_draw_layout(window, gc, spectrum_x_margin - 8 + i, spectrum_size_y
 				+ spectrum_top_margin + 5, layout);
+		g_object_unref(layout);
 		freq += scale;
 	}

@@ -626,6 +627,7 @@ void lingot_mainframe_draw_spectrum(LingotMainFrame* frame) {
 	layout = gtk_widget_create_pango_layout(frame->spectrum_area, buff);
 	pango_layout_set_font_description(layout, spectrum_legend_font_desc);
 	gdk_draw_layout(window, gc, spectrum_x_margin - 6, 2, layout);
+	g_object_unref(layout);

 	int grid_height = (int) (PLOT_GAIN*log10(pow(10.0, grid_db_height/10.0))); // dB.
 	j = 0;
@@ -639,6 +641,7 @@ void lingot_mainframe_draw_spectrum(LingotMainFrame* frame) {
 		pango_layout_set_font_description(layout, spectrum_legend_font_desc);
 		gdk_draw_layout(window, gc, 2, spectrum_size_y + spectrum_top_margin
 				- i - 5, layout);
+		g_object_unref(layout);

 		gdk_draw_line(window, gc, spectrum_x_margin, spectrum_size_y
 				+ spectrum_top_margin - i, spectrum_x_margin + spectrum_size_x,