Added the required gdk/gdk.h include before gdkcairo.h in maingui.c to satisfy GDK header include order requirements on Windows builds.

Added cairo surface tracking and context creation helpers for xtext rendering, including state initialization for the new draw surface field.

Replaced GdkPixmap-based offscreen text buffering with cairo surfaces and routed rendering/underline/strikethrough operations through the cairo context helper.

src/fe-gtk/xtext.h

@@ -132,6 +132,7 @@ struct _GtkXText
 	GtkAdjustment *adj;
 	GdkPixmap *pixmap;				/* 0 = use palette[19] */
 	GdkDrawable *draw_buf;			/* points to ->window */
+	cairo_surface_t *draw_surface;	/* temporary surface for offscreen draws */
 	GdkCursor *hand_cursor;
 	GdkCursor *resize_cursor;