[Bug 122406] New: [sidebar] Switching panels disposes the UI element

[bu...@apache.org]

https://issues.apache.org/ooo/show_bug.cgi?id=122406

            Bug ID: 122406
        Issue Type: DEFECT
           Summary: [sidebar] Switching panels disposes the UI element
           Product: General
           Version: AOO400-dev
          Hardware: All
                OS: All
            Status: CONFIRMED
          Severity: normal
          Priority: P3
         Component: ui
          Assignee: issues@openoffice.apache.org
          Reporter: arielch@apache.org
                CC: issues@openoffice.apache.org
            Blocks: 121420

- New Writer document
- Activate the gallery panel in the sidebar
- select a different image from the one that is already selected
- switch to the navigator panel, select "Hyperlinks"
- Switch back to the gallery: the image you have selected is no longer selected
- Switch back to the navigator: "Hyperlinks" is no longer selected

>From the user perspective, this might be not user-friendly.
>From the "technical" aspect, this is a waste of resources, the UI element is
recreated every time the user switches panels; as side effect, unless the panel
implementation stores its state, the panel state is lost having the effect
described above.

The root cause is that sfx2::sidebar::Panel::Dispose() disposed the UI element.
trunk/main/sfx2/source/sidebar/Panel.cxx

While later initialization of the UI element when the respective deck is
activated is good for performance, destroying the panels is not.

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[Bug 122406] [sidebar] Switching panels disposes the UI element

[bu...@apache.org]

https://issues.apache.org/ooo/show_bug.cgi?id=122406

Andre <aw...@googlemail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Blocks|121420                      |122257

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[Bug 122406] [sidebar] Switching panels disposes the UI element

[bu...@apache.org]

https://issues.apache.org/ooo/show_bug.cgi?id=122406

Andre <aw...@googlemail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |awf.aoo@googlemail.com
         Issue Type|DEFECT                      |ENHANCEMENT

--- Comment #1 from Andre <aw...@googlemail.com> ---
I am changing the issue type to enhancement.  I agree that a form of caching
might improve usability in a few cases but the state of most panels is defined
by items which belong to the document and therefore is already persistent.

Adding caching will open its own can of worms.  I did not implement caching of
panels because:

- No premature optimization.

- In the beginning the Impress panels where still tied to view shells.  Caching
them would have been a major undertaking.

- We don't have a performance problem (to my knowledge).

- Panels in the cache still need some parent window.  Changing parents of
controls that are not designed for that may or may not work.

- Caching panels of unknown implementation and complexity may require a good
caching strategy to avoid allocating too many resources.

- Most panels are not designed to be dormant for an extended period of time. 
They may have listeners and might react to events which can lead to unexpected
results.

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