patch 8.1.1866: modeless selection in GUI does not work properly

Problem:    Modeless selection in GUI does not work properly.
Solution:   Avoid going beyond the end of the line. (closes #4783)

src/ui.c

@@ -1619,12 +1619,12 @@ clip_copy_modeless_selection(int both UNUSED)
 
 	if (row == row2)
 	    end_col = col2;
-	else
 #ifdef FEAT_TEXT_PROP
+	else if (clip_star.max_col < Columns)
 	    end_col = clip_star.max_col + 1;
-#else
-	    end_col = Columns;
 #endif
+	else
+	    end_col = Columns;
 
 	line_end_col = clip_get_line_end(&clip_star, row);
 
@@ -1797,7 +1797,7 @@ clip_get_line_end(Clipboard_T *cbd UNUSED, int row)
 	return 0;
     for (i =
 #ifdef FEAT_TEXT_PROP
-	    cbd->max_col + 1;
+	    cbd->max_col >= screen_Columns ? screen_Columns : cbd->max_col + 1;
 #else
 	    screen_Columns;
 #endif

src/version.c

@@ -769,6 +769,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1866,
 /**/
     1865,
 /**/