diff --git a/gnoemoe/widgets/gm-editor-view.c b/gnoemoe/widgets/gm-editor-view.c
index c10fd3f..627ad5b 100644
--- a/gnoemoe/widgets/gm-editor-view.c
+++ b/gnoemoe/widgets/gm-editor-view.c
@@ -9,9 +9,12 @@
 #include "../gm-pixbuf.h"
 #include "../gm-support.h"
 #include "../gm-debug.h"
+#include "../gm-string.h"
 #include "../gm-options.h"
 #include "../gm-color-table.h"
 #include "../gm-app.h"
+#include "../parser/gm-parser.h"
+
 #include "gm-searchable.h"
 
 #define GM_EDITOR_VIEW_GET_PRIVATE(object)( \
@@ -22,6 +25,18 @@ struct _GmEditorViewPrivate {
 	GmWorld *world;
 	GmEditor *editor;
 	
+	GtkExpander *expander;
+	GtkWidget *message_area;
+	GtkWidget *error_label;
+	GtkWidget *warning_label;
+	GtkWidget *error_frame;
+	GtkWidget *warning_frame;
+	
+	gboolean set_style;
+	guint timeout_handler;
+	guint hide_error_handler;
+	gboolean expanding;
+	gboolean was_expanded;
 	GtkSourceView *source_view;
 };
 
@@ -47,12 +62,19 @@ void on_gm_editor_view_saveclose_clicked(GtkToolButton *button,
 		GmEditorView *view);
 void on_gm_editor_view_close_clicked(GtkToolButton *button, 
 		GmEditorView *view);
+void on_gm_editor_view_execute_clicked(GtkToolButton *button, 
+		GmEditorView *view);
+
 void on_gm_editor_view_editor_saved(GmEditor *editor, GmEditorView *view);
 
 void on_gm_editor_view_font_changed(GmColorTable *color_table, 
 		gchar const *desc, GmEditorView *view);
 void on_gm_editor_view_modified_changed(GtkTextBuffer *buffer, 
 		GmEditorView *view);
+void on_gm_editor_view_changed(GtkTextBuffer *buffer, 
+		GmEditorView *view);
+void on_gm_editor_view_expander(GObject *object, GParamSpec *param_spec,
+		GmEditorView *view);
 
 G_DEFINE_TYPE_EXTENDED(GmEditorView, gm_editor_view, GTK_TYPE_VBOX, 0, \
 		G_IMPLEMENT_INTERFACE(GM_TYPE_SEARCHABLE, \
@@ -74,7 +96,14 @@ gm_editor_view_searchable_get_text_view(GmSearchable *sea) {
 
 static void
 gm_editor_view_finalize(GObject *object) {
-	//GmEditorView *obj = GM_EDITOR_VIEW(object);
+	GmEditorView *obj = GM_EDITOR_VIEW(object);
+	
+	if (obj->priv->timeout_handler) {
+		g_source_remove(obj->priv->timeout_handler);
+	}
+	if (obj->priv->hide_error_handler) {
+		g_source_remove(obj->priv->hide_error_handler);
+	}
 	
 	G_OBJECT_CLASS(gm_editor_view_parent_class)->finalize(object);
 }
@@ -111,7 +140,7 @@ gm_editor_view_class_init(GmEditorViewClass *klass) {
 }
 
 GtkSourceView *
-gm_editor_create_source_view(GmEditorView *view) {
+gm_editor_view_create_source_view(GmEditorView *view) {
 	GtkTextBuffer *buffer;
 	GtkWidget *source_view;
 	GtkTextIter iter;
@@ -128,6 +157,7 @@ gm_editor_create_source_view(GmEditorView *view) {
 		gtk_source_buffer_set_language(GTK_SOURCE_BUFFER(buffer), language);
 	}
 
+	gtk_source_buffer_begin_not_undoable_action(GTK_SOURCE_BUFFER(buffer));
 	gtk_text_buffer_get_end_iter(buffer, &iter);
 
 	for (lines = gm_editor_lines(view->priv->editor); lines; 
@@ -140,6 +170,7 @@ gm_editor_create_source_view(GmEditorView *view) {
 		}
 	}
 
+	gtk_source_buffer_end_not_undoable_action(GTK_SOURCE_BUFFER(buffer));
 	gtk_text_buffer_set_modified(buffer, FALSE);
 	
 	st = gtk_source_tag_style_new();
@@ -169,19 +200,109 @@ gm_editor_create_source_view(GmEditorView *view) {
 		gtk_source_buffer_set_highlight(GTK_SOURCE_BUFFER(buffer), FALSE);
 	}
 
+	gtk_text_buffer_create_tag(buffer, "gm_error", "underline", 
+			PANGO_UNDERLINE_ERROR, NULL);
+
 	g_signal_connect(buffer, "modified_changed", 
 			G_CALLBACK(on_gm_editor_view_modified_changed), view);
+	g_signal_connect(buffer, "changed",
+			G_CALLBACK(on_gm_editor_view_changed), view);
+
 	gtk_widget_show(source_view);
 
 	return GTK_SOURCE_VIEW(source_view);
 }
 
+static gboolean
+gm_editor_view_paint_message_area(GtkWidget *widget, GdkEventExpose *event,
+		GmEditorView *view) {
+	gtk_paint_flat_box(widget->style, widget->window, GTK_STATE_NORMAL,
+			GTK_SHADOW_OUT, NULL, widget, "tooltip",
+			widget->allocation.x + 1, widget->allocation.y + 1,
+			widget->allocation.width - 2, widget->allocation.height - 2);
+
+	return FALSE;
+}
+
+static void
+gm_editor_view_message_area_style_set(GtkWidget *widget, GtkStyle *prev,
+		GmEditorView *view) {
+	GtkTooltips *tooltips;
+	GtkStyle *style;
+    
+	if (view->priv->set_style) {
+		return;
+	}
+	
+	tooltips = gtk_tooltips_new();
+	g_object_ref(G_OBJECT(tooltips));
+	gtk_object_sink(GTK_OBJECT(tooltips));
+
+	gtk_tooltips_force_window(tooltips);
+	gtk_widget_ensure_style(tooltips->tip_window);
+	style = gtk_widget_get_style(tooltips->tip_window);
+	
+	view->priv->set_style = TRUE;
+	gtk_widget_set_style(widget, style);
+	view->priv->set_style = FALSE;
+	g_object_unref(tooltips);
+}
+
+static void
+gm_editor_view_create_message_area(GmEditorView *view) {
+	GtkWidget *message_area = gtk_vbox_new(FALSE, 6);
+	GtkWidget *align;
+	GtkWidget *lbl;
+	gtk_container_set_border_width(GTK_CONTAINER(message_area), 10);
+	
+	g_signal_connect(message_area, "expose_event", 
+			G_CALLBACK(gm_editor_view_paint_message_area), view);
+	g_signal_connect(message_area, "style-set",
+			G_CALLBACK(gm_editor_view_message_area_style_set), view);
+			
+	view->priv->message_area = message_area;
+	
+	lbl = gtk_label_new(NULL);
+	gtk_label_set_markup(GTK_LABEL(lbl), _("<b>Errors</b>"));
+	view->priv->error_frame = gtk_frame_new(NULL);
+	gtk_frame_set_shadow_type(GTK_FRAME(view->priv->error_frame), 
+			GTK_SHADOW_NONE);
+	gtk_frame_set_label_widget(GTK_FRAME(view->priv->error_frame), lbl);
+	
+	view->priv->error_label = gtk_label_new(NULL);
+	
+	gtk_misc_set_alignment(GTK_MISC(view->priv->error_label), 0.0, 0.0);
+	align = gtk_alignment_new(0.0, 0.0, 0.0, 0.0);
+	gtk_alignment_set_padding(GTK_ALIGNMENT(align), 0, 0, 12, 0);
+	
+	gtk_container_add(GTK_CONTAINER(align), view->priv->error_label);
+	gtk_container_add(GTK_CONTAINER(view->priv->error_frame), align);
+	gtk_box_pack_start(GTK_BOX(message_area), view->priv->error_frame, TRUE, 
+			TRUE, 0);
+	
+	lbl = gtk_label_new(NULL);
+	gtk_label_set_markup(GTK_LABEL(lbl), _("<b>Warnings</b>"));
+	view->priv->warning_frame = gtk_frame_new(NULL);
+	gtk_frame_set_shadow_type(GTK_FRAME(view->priv->warning_frame), 
+			GTK_SHADOW_NONE);
+	gtk_frame_set_label_widget(GTK_FRAME(view->priv->warning_frame), lbl);
+	view->priv->warning_label = gtk_label_new(NULL);
+	
+	gtk_misc_set_alignment(GTK_MISC(view->priv->warning_label), 0.0, 0.0);
+	align = gtk_alignment_new(0.0, 0.0, 0.0, 0.0);
+	gtk_alignment_set_padding(GTK_ALIGNMENT(align), 0, 0, 12, 0);
+	
+	gtk_container_add(GTK_CONTAINER(align), view->priv->warning_label);
+	gtk_container_add(GTK_CONTAINER(view->priv->warning_frame), align);
+	gtk_box_pack_start(GTK_BOX(message_area), view->priv->warning_frame, TRUE, TRUE, 0);
+}
+
 static void
 gm_editor_view_init(GmEditorView *obj) {
-	GtkWidget *toolbar, *item;
+	GtkWidget *toolbar, *item, *expander, *tmp;
 	obj->priv = GM_EDITOR_VIEW_GET_PRIVATE(obj);
 	
-	gtk_box_set_spacing(GTK_BOX(obj), 6);
+	gtk_box_set_spacing(GTK_BOX(obj), 0);
 	gtk_box_set_homogeneous(GTK_BOX(obj), FALSE);
 	
 	toolbar = gtk_toolbar_new();
@@ -202,8 +323,32 @@ gm_editor_view_init(GmEditorView *obj) {
 			G_CALLBACK(on_gm_editor_view_close_clicked), obj);
 	gtk_container_add(GTK_CONTAINER(toolbar), item);
 	
+	item = GTK_WIDGET(gtk_tool_button_new_from_stock(GTK_STOCK_EXECUTE));
+	g_signal_connect(item, "clicked",
+			G_CALLBACK(on_gm_editor_view_execute_clicked), obj);
+	gtk_container_add(GTK_CONTAINER(toolbar), item);
+
+	item = GTK_WIDGET(gtk_separator_tool_item_new());
+	gtk_container_add(GTK_CONTAINER(toolbar), item);
+	
+	item = GTK_WIDGET(gtk_tool_item_new());
+	tmp = gtk_alignment_new(0.0, 1.0, 0.0, 0.0);
+	expander = gtk_expander_new(NULL);
+	g_signal_connect(expander, "notify::expanded",
+			G_CALLBACK(on_gm_editor_view_expander), obj);
+
+	gtk_container_add(GTK_CONTAINER(tmp), expander);
+	gtk_container_add(GTK_CONTAINER(item), tmp);
+	gtk_container_add(GTK_CONTAINER(toolbar), item);
+	
 	gtk_box_pack_start(GTK_BOX(obj), toolbar, FALSE, FALSE, 0);
 	gtk_widget_show_all(toolbar);
+	
+	gtk_widget_hide(expander);
+	obj->priv->expander = GTK_EXPANDER(expander);
+	
+	gm_editor_view_create_message_area(obj);
+	gtk_box_pack_start(GTK_BOX(obj), obj->priv->message_area, FALSE, FALSE, 0);
 }
 
 GmEditorView *
@@ -213,7 +358,7 @@ gm_editor_view_new(GmWorld *world, GmEditor *editor) {
 	
 	obj->priv->editor = editor;
 	obj->priv->world = world;
-	obj->priv->source_view = gm_editor_create_source_view(obj);
+	obj->priv->source_view = gm_editor_view_create_source_view(obj);
 
     srl = gtk_scrolled_window_new(NULL, NULL);
     gtk_widget_show(srl);
@@ -221,7 +366,7 @@ gm_editor_view_new(GmWorld *world, GmEditor *editor) {
 			GTK_POLICY_AUTOMATIC, GTK_POLICY_AUTOMATIC);
 
 	gtk_container_add(GTK_CONTAINER(srl), GTK_WIDGET(obj->priv->source_view));
-	gtk_box_pack_start(GTK_BOX(obj), srl, TRUE, TRUE, 0);
+	gtk_box_pack_end(GTK_BOX(obj), srl, TRUE, TRUE, 0);
 	
 	g_signal_connect(gm_app_color_table(gm_app_instance()), "font_changed",
 			G_CALLBACK(on_gm_editor_view_font_changed), obj);
@@ -255,6 +400,179 @@ gm_editor_view_save(GmEditorView *view) {
 	gm_editor_save(view->priv->editor);
 }
 
+gboolean
+gm_editor_view_no_errors(GmEditorView *view) {
+	gtk_widget_hide(GTK_WIDGET(view->priv->expander));
+	return FALSE;
+}
+
+void
+gm_editor_view_parse_error(GmEditorView *view, GmParserError *error, 
+		GString **str) {
+	GtkTextBuffer *buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(
+			view->priv->source_view));
+	GtkTextIter start, end;
+	gchar *msg;
+	
+	if (error->ch == 0) {
+		gtk_text_buffer_get_iter_at_line(buffer, &start, 
+				error->line - 1);
+		msg = g_markup_printf_escaped(_("<u>Line %d</u>: %s\n"), error->line, 
+				error->message);
+	} else {
+		// Underline line
+		gtk_text_buffer_get_iter_at_line(buffer, &start, error->line);
+		msg = g_markup_printf_escaped(_("<u>Line %d:%d</u>: %s\n"), 
+				error->line + 1, error->ch + 1, error->message);
+	}
+	
+	if (!*str) {
+		*str = g_string_new(msg);
+	} else {
+		*str = g_string_append(*str, msg);
+	}
+	
+	g_free(msg);
+	end = start;
+	
+	if (error->ch != 0) {
+		gtk_text_iter_forward_chars(&start, error->ch - 1);
+	}
+	
+	gtk_text_iter_forward_to_line_end(&end);
+	gtk_text_buffer_apply_tag_by_name(buffer, "gm_error", &start, &end);
+}
+
+enum {
+	SYNTAX_OK = 0,
+	SYNTAX_ERRORS = 1 << 0,
+	SYNTAX_WARNINGS = 1 << 1
+};
+
+int
+gm_editor_view_parse(GmEditorView *view) {
+	gchar *text;
+	GtkTextIter start, end;
+	GList *lines;
+	GmParserResult *result;
+	GList *errors;
+	GtkTextBuffer *buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(
+			view->priv->source_view));
+	gchar *msg;
+	GString *str = NULL, *lbl = NULL;
+	int ret = SYNTAX_OK;
+	
+	if (view->priv->hide_error_handler) {
+		g_source_remove(view->priv->hide_error_handler);
+	}
+	
+	gtk_text_buffer_get_bounds(buffer, &start, &end);
+	text = gtk_text_buffer_get_text(buffer, &start, &end, TRUE);
+	lines = gm_string_split(text);
+	
+	result = gm_parser_parse(lines);
+	
+	gtk_text_buffer_remove_tag_by_name(buffer, "gm_error", &start, &end);
+	
+	if (!result->isOk) {
+		if (result->errors) {
+			for (errors = result->errors; errors; errors = errors->next) {
+				gm_editor_view_parse_error(view, (GmParserError *)(errors->data),
+						&str);
+			}
+			
+			str = g_string_truncate(str, str->len - 1);
+			gtk_label_set_markup(GTK_LABEL(view->priv->error_label), str->str);
+			gtk_widget_show_all(view->priv->error_frame);
+			g_string_free(str, TRUE);
+			str = NULL;
+
+			if (g_list_length(result->errors) == 1) {
+				msg = g_strdup(_("There is 1 error"));
+			} else {
+				msg = g_strdup_printf(_("There are %d errors"), 
+						g_list_length(result->errors));
+			}
+			
+			lbl = g_string_new(msg);
+			g_free(msg);
+			
+			ret |= SYNTAX_ERRORS;
+		} else {
+			gtk_widget_hide(view->priv->error_frame);
+		}
+		if (result->warnings) {
+			for (errors = result->warnings; errors; errors = errors->next) {
+				gm_editor_view_parse_error(view, (GmParserError *)(errors->data),
+						&str);		
+			}
+			
+			str = g_string_truncate(str, str->len - 1);
+			gtk_label_set_markup(GTK_LABEL(view->priv->warning_label), 
+					str->str);
+			gtk_widget_show_all(view->priv->warning_frame);
+			g_string_free(str, TRUE);
+			
+			if (g_list_length(result->warnings) == 1) {
+				if (!lbl) {
+					msg = g_strdup(_("There is 1 warning"));
+				} else {
+					msg = g_strdup_printf(_(" and 1 warning"));				
+				}
+			} else {
+				if (!lbl) {
+					msg = g_strdup_printf(_("There are %d warnings"), 
+							g_list_length(result->warnings));
+				} else {
+					msg = g_strdup_printf(_(" and %d warnings"), 
+							g_list_length(result->warnings));				
+				}
+			}
+			
+			if (!lbl) {
+				lbl = g_string_new(msg);
+			} else {
+				lbl = g_string_append(lbl, msg);
+			}
+			
+			g_free(msg);
+			
+			ret |= SYNTAX_WARNINGS;
+		} else {
+			gtk_widget_hide(view->priv->warning_frame);
+		}
+		
+		gtk_widget_set_sensitive(GTK_WIDGET(view->priv->expander), TRUE);
+		gtk_expander_set_label(view->priv->expander, lbl->str);
+		g_string_free(lbl, TRUE);
+		gtk_widget_show(GTK_WIDGET(view->priv->expander));
+		
+		if (view->priv->was_expanded && 
+				!gtk_expander_get_expanded(view->priv->expander)) {
+			view->priv->expanding = TRUE;
+			gtk_expander_set_expanded(view->priv->expander, TRUE);
+			view->priv->expanding = FALSE;
+		}
+	} else {
+		gtk_expander_set_label(view->priv->expander, _("There are no errors"));
+		
+		view->priv->expanding = TRUE;
+		gtk_expander_set_expanded(view->priv->expander, FALSE);
+		view->priv->expanding = FALSE;
+
+		gtk_widget_set_sensitive(GTK_WIDGET(view->priv->expander), FALSE);
+		gtk_widget_hide(view->priv->message_area);
+		view->priv->hide_error_handler = g_timeout_add(3000, 
+				(GSourceFunc)gm_editor_view_no_errors, view);
+	}
+	
+	gm_parser_result_free(result);
+	gm_g_list_free_simple(lines);
+	g_free(text);
+	
+	return ret;
+}
+
 /* Callbacks */
 
 void
@@ -296,9 +614,64 @@ on_gm_editor_view_close_clicked(GtkToolButton *button,
 	gm_editor_close(view->priv->editor);
 }
 
+void
+on_gm_editor_view_execute_clicked(GtkToolButton *button, 
+		GmEditorView *view) {
+	int ret = gm_editor_view_parse(view);
+	
+	if (ret == SYNTAX_OK) {
+		gtk_expander_set_expanded(view->priv->expander, FALSE);
+		gtk_widget_hide(view->priv->message_area);
+		gm_info_dialog(_("No errors are found"), NULL);
+	} else {
+		gtk_expander_set_expanded(view->priv->expander, TRUE);
+		gtk_widget_show_all(view->priv->message_area);
+	}
+}
+
+
 void
 on_gm_editor_view_modified_changed(GtkTextBuffer *buffer, 
 		GmEditorView *view) {
 	g_signal_emit(view, gm_editor_view_signals[MODIFIED_CHANGED], 0, 
 			gtk_text_buffer_get_modified(buffer));
 }
+
+gboolean
+gm_editor_view_timeout(GmEditorView *view) {
+	gm_editor_view_parse(view);
+	view->priv->timeout_handler = 0;
+	return FALSE;
+}
+
+void
+on_gm_editor_view_changed(GtkTextBuffer *buffer, 
+		GmEditorView *view) {
+	if (view->priv->timeout_handler != 0) {
+		g_source_remove(view->priv->timeout_handler);
+	}
+	
+	if (gm_options_get_int(gm_app_options(gm_app_instance()), 
+			"auto_check_syntax")) {
+		view->priv->timeout_handler = g_timeout_add(500, 
+				(GSourceFunc)gm_editor_view_timeout, view);
+	}
+}
+
+void
+on_gm_editor_view_expander(GObject *object, GParamSpec *param_spec,
+		GmEditorView *view) {
+	if (gtk_expander_get_expanded(view->priv->expander)) {
+		if (!view->priv->expanding) {
+			view->priv->was_expanded = TRUE;
+		}
+		
+		gtk_widget_show(view->priv->message_area);
+	} else {
+		if (!view->priv->expanding) {
+			view->priv->was_expanded = FALSE;
+		}
+		
+		gtk_widget_hide(view->priv->message_area);
+	}
+}