fixed the delayed selection paint by changing gtk_xtext_render_ents() to queue a GTK redraw when called outside ::draw on GTK3, instead of attempting direct window painting. This addresses the “double-click/drag selection only appears after some other window change” behavior.

Added an in-code comment explaining why this path is needed (GTK3/Wayland frame-driven presentation).

src/fe-gtk/xtext.c

@@ -195,6 +195,8 @@ static void gtk_xtext_search_textentry_fini (gpointer, gpointer);
 static void gtk_xtext_search_fini (xtext_buffer *);
 static gboolean gtk_xtext_search_init (xtext_buffer *buf, const gchar *text, gtk_xtext_search_flags flags, GError **perr);
 static char * gtk_xtext_get_word (GtkXText * xtext, int x, int y, textentry ** ret_ent, int *ret_off, int *ret_len, GSList **slp);
+static gboolean gtk_xtext_word_select_char (const unsigned char *ch);
+static gboolean gtk_xtext_get_word_select_range (GtkXText *xtext, int x, int y, textentry **ret_ent, int *ret_off, int *ret_len);
 
 static inline void
 gtk_xtext_cursor_unref (GdkCursor *cursor)
@@ -1856,10 +1858,12 @@ gtk_xtext_selection_draw (GtkXText * xtext, GdkEventMotion * event, gboolean ren
 	if (xtext->word_select)
 	{
 		/* a word selection cannot be started if the cursor is out of bounds in gtk_xtext_button_press */
-		gtk_xtext_get_word (xtext, low_x, low_y, NULL, &low_offs, NULL, NULL);
+		if (!gtk_xtext_get_word_select_range (xtext, low_x, low_y, NULL, &low_offs, NULL))
+			gtk_xtext_get_word (xtext, low_x, low_y, NULL, &low_offs, NULL, NULL);
 
 		/* in case the cursor is out of bounds we keep offset_end from gtk_xtext_find_char and fix the length */
-		if (gtk_xtext_get_word (xtext, high_x, high_y, NULL, &high_offs, &high_len, NULL) == NULL)
+		if (!gtk_xtext_get_word_select_range (xtext, high_x, high_y, NULL, &high_offs, &high_len) &&
+			 gtk_xtext_get_word (xtext, high_x, high_y, NULL, &high_offs, &high_len, NULL) == NULL)
 			high_len = high_offs == high_ent->str_len? 0: -1; /* -1 for the space, 0 if at the end */
 		high_offs += high_len;
 		if (low_y < 0)
@@ -2134,6 +2138,57 @@ gtk_xtext_get_word (GtkXText * xtext, int x, int y, textentry ** ret_ent,
 	return word;
 }
 
+static gboolean
+gtk_xtext_word_select_char (const unsigned char *ch)
+{
+	gunichar uc;
+
+	if (!ch || !*ch)
+		return FALSE;
+
+	uc = g_utf8_get_char_validated ((const gchar *)ch, -1);
+	if (uc == (gunichar)-1 || uc == (gunichar)-2)
+		return FALSE;
+	return g_unichar_isalnum (uc) || uc == '_' || uc == '-';
+}
+
+static gboolean
+gtk_xtext_get_word_select_range (GtkXText *xtext, int x, int y, textentry **ret_ent, int *ret_off, int *ret_len)
+{
+	textentry *ent;
+	int offset;
+	unsigned char *start, *end;
+
+	ent = gtk_xtext_find_char (xtext, x, y, &offset, NULL);
+	if (!ent || offset < 0 || offset >= ent->str_len)
+		return FALSE;
+
+	start = ent->str + offset;
+	end = g_utf8_find_next_char (start, ent->str + ent->str_len);
+	if (!gtk_xtext_word_select_char (start))
+		return FALSE;
+
+	while (start > ent->str)
+	{
+		unsigned char *prev = g_utf8_find_prev_char (ent->str, start);
+		if (!prev || !gtk_xtext_word_select_char (prev))
+			break;
+		start = prev;
+	}
+
+	while (end && end < ent->str + ent->str_len && gtk_xtext_word_select_char (end))
+		end = g_utf8_find_next_char (end, ent->str + ent->str_len);
+
+	if (ret_ent)
+		*ret_ent = ent;
+	if (ret_off)
+		*ret_off = (int)(start - ent->str);
+	if (ret_len)
+		*ret_len = (int)(end - start);
+
+	return TRUE;
+}
+
 static void
 gtk_xtext_unrender_hilight (GtkXText *xtext)
 {
@@ -2581,7 +2636,8 @@ gtk_xtext_button_press (GtkWidget * widget, GdkEventButton * event)
 	if (event->type == GDK_2BUTTON_PRESS)	/* WORD select */
 	{
 		gtk_xtext_check_mark_stamp (xtext, mask);
-		if (gtk_xtext_get_word (xtext, x, y, &ent, &offset, &len, 0))
+		if (gtk_xtext_get_word_select_range (xtext, x, y, &ent, &offset, &len) ||
+			 gtk_xtext_get_word (xtext, x, y, &ent, &offset, &len, 0))
 		{
 			if (len == 0)
 				return FALSE;
@@ -4324,6 +4380,21 @@ gtk_xtext_nth (GtkXText *xtext, int line, int *subline)
 static int
 gtk_xtext_render_ents (GtkXText * xtext, textentry * enta, textentry * entb)
 {
+	/*
+	 * On GTK3 (especially Wayland), event handlers are outside ::draw and direct
+	 * window painting may not be presented immediately. Queue a frame instead so
+	 * selections appear right away.
+	 */
+#if HAVE_GTK3
+	if (xtext->draw_cr == NULL)
+	{
+		GtkWidget *w = GTK_WIDGET (xtext);
+		if (gtk_widget_get_realized (w))
+			gtk_widget_queue_draw (w);
+		return 0;
+	}
+#endif
+
 	textentry *ent, *orig_ent, *tmp_ent;
 	int line;
 	int lines_max;