Fix glitch in showbuf window with odd-numbered width

src/uifc/uifc32.c

@@ -2798,7 +2798,7 @@ void showbuf(int mode, int left, int top, int width, int height, char *title, ch
 			tmp_buffer2[k].ch='u'; k++;
 			tmp_buffer2[k].ch='e'; k+=2;
 			tmp_buffer2[k].ch=api->chars->help_hitanykey_right; k++;
-			for(j=k;j<k+(((width-4)/2-12));j++)
+			for(j=k;j<k+(((width-4)/2-12))+(width&1);j++)
 				tmp_buffer2[j].ch=api->chars->help_bottom;
 		}
 		else {