+ if (ABS(dy) == SCROLL_PAGE)
+ step = num_page_entries - 1;
+
+ if (dy < 0 && ti->cl_first > 0)
+ {
+ /* scroll page/line up */
+
+ ti->cl_first -= step;
+ if (ti->cl_first < 0)
+ ti->cl_first = 0;
+
+ drawChooseTreeList(ti->cl_first, num_page_entries, ti);
+ drawChooseTreeInfo(ti->cl_first + ti->cl_cursor, ti);
+ drawChooseTreeCursor(ti->cl_cursor, FC_RED);
+ AdjustChooseTreeScrollbar(SCREEN_CTRL_ID_SCROLL_VERTICAL,
+ ti->cl_first, ti);
+ }
+ else if (dy > 0 && ti->cl_first + num_page_entries < num_entries)
+ {
+ /* scroll page/line down */
+
+ ti->cl_first += step;
+ if (ti->cl_first + num_page_entries > num_entries)
+ ti->cl_first = MAX(0, num_entries - num_page_entries);
+
+ drawChooseTreeList(ti->cl_first, num_page_entries, ti);
+ drawChooseTreeInfo(ti->cl_first + ti->cl_cursor, ti);
+ drawChooseTreeCursor(ti->cl_cursor, FC_RED);
+ AdjustChooseTreeScrollbar(SCREEN_CTRL_ID_SCROLL_VERTICAL,
+ ti->cl_first, ti);
+ }