PR# 19738 EV_GRID.vertical_scroll_bar.step_forward / backward -- buggy behaviour

Problem Report Summary
Submitter: HowardThomsonSurrey
Category: EiffelVision
Priority: Low
Date: 2021/04/05
Class: Bug
Severity: Non-critical
Number: 19738
Release: 19.12
Confidential: No
Status: Open
Environment: linux
Synopsis: EV_GRID.vertical_scroll_bar.step_forward / backward -- buggy behaviour

I have an agent attached to pointer_button_press_actions which calls vertical_scroll_bar.step_forward [step_backward] in the context of a descendant of EV_GRID.

When the scroll_bar is visible, mouse_wheel actions in the display area behave correctly, consistent with the content being visible with no top/bottom gaps.

When the scroll_bar is not visible, mouse_wheel events scroll the contents off the top of the screen ...
To Reproduce
I may submit a reduced code sample to reproduce this at a later date ...
Problem Report Interactions