/tmp/ccmXu4gf.o: In function `expose_cb':
callbacks.c:(.text+0x117): undefined reference to `GDK_WINDOW_XWINDOW'
callbacks.c:(.text+0x11e): undefined reference to `gst_x_overlay_get_type'
callbacks.c:(.text+0x139): undefined reference to `gst_x_overlay_set_xwindow_id'
collect2: ld returned 1 exit status