Moving TabFolderLayout into SWT.

[deepika-u]

Moving TabFolderLayout into SWT.

Fixes #1317

This pr needs to be merged first and later eclipse-platform/eclipse.platform.ui#2186

[github-actions]

Test Results

  284 files   -   201    284 suites   - 201   4m 56s ⏱️ - 3m 55s
4 158 tests ±    0  4 150 ✅ +    1   8 💤 ± 0  0 ❌  - 1 
8 246 runs   - 8 140  8 188 ✅  - 8 105  58 💤  - 34  0 ❌  - 1 

Results for commit 314211c. ± Comparison against base commit 02e20d6.

♻️ This comment has been updated with latest results.

[deepika-u]

@laeubi @merks : Can this pr be merged? or anything else needs to be done?

[merks]

Has this been rebased on master?

I see this as the current version of SWT:

[laeubi]

Has this been rebased on master?

Done!

[akurtakov]

This class totally lacks documentation compared to rest of SWT. From just looking at it I have zero clue what/why/how/when to use it. Please add proper documentation before it can be accepted in SWT.

[laeubi]

This class totally lacks documentation compared to rest of SWT.

Can you be more specific?

I have zero clue what/why/how/when to use it

e.g I see this

This layout controls the position and size
of the children of a tab folder.

As explained in the referenced issues, this is somehow not often used directly (but not prohibited of course) if I look for example at CTabFolderLayout it has similar (quite basic) documentation.

So while better documentation is always good, I think its hard to ask the person that wants to help deduplication to do it, so I would more see this as something for all SWT/Platform commiters to enhance after we have deduplicated the code if there are anything left that is really unclear in its usage.

[laeubi]

Can this really be package private?

[akurtakov]

@deepika-u You haven't answered here? How is this supposed to be used from platform.ui?

[deepika-u]

Yeah totally agree when no modifier is mentioned it'll be defaulted to private. For this class to be available for platform.ui it needs to be public. It is done now.

[laeubi]

I think it would be good if this PR would include setting this layout in the TabFolder as a default layout, this would also make it more clear how/when/why use it.

If it should be package private I think it needs to reside in the same package as TabFolder

[akurtakov]

Well, I still don't understand what the effects of using this one are.
P.S. Don't even get me started on all C(ustom)* widgets and friends - they should be deleted IMO.

[akurtakov]

Also looking into the issue all the classes that are to be deduplicated are "internal" so they are not supposed to be generally useful which explains (to some extend) lack of documentation. I don't ask for big documentation but at least some basic one on what the effects of using it are.

[laeubi]

Well, I still don't understand what the effects of using this one are.

The effect is that otherwise you get randomly wrong display of Tabs, see

• Move TabFolderLayout into SWT and set it as a default in TabFolder #1317

Today I debugged some issues with TabFolder and noticed that it at least behaves strange if tabs are added dynamically, after investigate a little bit more I tried to fix it with an own Layout as usual layout mangers (like FillLayout) get sometimes confused as TabFolder has more childs than are actually displayed.

so they are not supposed to be generally useful

If they are not generally useful why we have 6 copies of the same code? ;-)

[akurtakov]

One more observation this seems to be used with CTabFolder from the platform.ui rather than TabFolder. What happens when used with TabFolder (some screenshots please)? It should be clear whether it's for one or the other or both TabFolders and if the later maybe clarified in the name.

[laeubi]

I use it for TabFolder (like reported on the issue), but the layout can be used for any component that wants TabFolder-Like behaviour (e.g. only showing all component at the full size of the composite stacked onto each other)

[akurtakov]

I use it for TabFolder (like reported on the issue), but the layout can be used for any component that wants TabFolder-Like behaviour (e.g. only showing all component at the full size of the composite stacked onto each other)

Consider putting such an explanation as a class comment :)