https://issues.apache.org/ooo/show_bug.cgi?id=121583
Bug ID: 121583
Issue Type: DEFECT
Summary: Vertical scrollbar scroll bar miscalculations
Classification: Application
Product: word processor
Version: AOO 3.4.1
Hardware: Mac
OS: Mac OSX, all
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: ui
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
This is an attempt to clarify the problems I see reported in Bug # 121266.
The vertical scroll bar on the mac version in a word processor window has an
area at the bottom reserved for several buttons. Thus the whole height of the
window is not used for the scroll bar. In all likelihood, these size of these
buttons was not understood and threw off some calculations regarding the usable
area of the scroll bar.
In this shorter scroll bar range, the visible thumb actually can appear in any
position, as it should. (However, it looks like a slight miscalculation of
thumb position allows it to overlap the top pixels of the buttons below it when
the thumb is in its bottom-most position.)
Now, even though the visible position of the thumb seems to be nearly correct
in its use of the visible space, the clickable area of the vertical scroll bar
is more restricted. This has some curious effects. The mapping of the clickable
range onto the visible range causes the thumb to be under your mouse when the
mouse is at the top of the scroll bar. However, as the mouse moves further
toward the bottom of the scroll bar, the visible thumb starts to move further
and further BELOW the mouse. By grabbing the thumb when it as at the top of the
scroll bar and dragging it slowly down, you can see that the thumb moves
progressively more and more below the cursor. In this way, you can discover the
approximate clickable range and how much it differs from the space in which the
scroll bar thumb moves.
When the visible thumb is at the bottom, you cannot "grab" it with the mouse,
since it is outside the clickable range. The user must guess at the where the
bottom of the clickable range is and click there to be able to grab the thumb.
The thumb then tracks the mouse, but is not visibly overlaid by the mouse until
the mouse approaches the top of the scroll bar.
This explains some effects described in Bug # 121266. There can be a "dead
zone" above the visible thumb when it as the bottom of the scroll bar, since
the miscalculated clickable range ends some distance above the thumb.
Strangely, there are two clickable areas (one for scrolling up and another for
scrolling down) which fall below this dead zone and even span the visible thumb
when at the bottom of the scroll bar. Perhaps these are byproducts of some code
intended to support a different scrolling mechanism on a different platform.
Also, if one has the visible thumb in the middle of the scroll bar, and the
system preferences are set so a click on one side of the thumb jumps in that
direction by one page, the results can be very confusing, since the program
thinks the visible thumb is in a different location from where it appears on
the screen. Thus, on the screen, the user thinks he is clicking above the thumb
but the program thinks he is clicking below it.
I see that this bug appears in a previous version of OpenOffice, which I've
been using (3.3.0). In addition, the same bug appears in LibreOffice. Hence, it
must date back to some code common to these products.
This bug is an annoyance. However, it works in a predictable fashion, if you
understand how it arises. I find that having my system preferences set to
position the document to a relative location on a click anywhere in the scroll
bar minimizes the problems.
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