Drag to close areas

Close an area by dragging an edge between two areas. Also works while dragging out a new area using the new area handle.

This patch should help new and existing users alike. It addresses one of my primary frustrations while learning to use Blender.

The challenge in this patch was that the current way of showing to the user that an area will be merged, the arrow overlay, wasn't obvious enough when the panel had been dragged to a small size. Instead I made the area snap over to one side if it'll be closed when the user releases the mouse button. I had some problems implementing this, so instead of actually moving the area over, it only renders with an offset, as if it's moved over. That may create problems if it continues to be rendered offset after the user lets go of the split, but this should never happen since the user's mouse interaction is tied up with the splitter dragging.

[brechtvl, 2012-06-03 10:31:41]

When you drag down the top info header (to view reports), and then drag it back
up, weird things happen, and the outliner header also gets hidden partially but
snaps back when you move the mouse into the outliner editor.

That's an example of a case that wouldn't be allowed to be close with dragging
the handles, but further, there's also a more general conflict here. Some users
will drag down an editor to just the size of the header, to move it out of the
way temporarily but not close it. With this change it's not possible anymore to
do this.

[Vino, 2012-06-03 17:52:56]

Thank you so much for taking the time to review both of these patches.

You bring up a good point with the top info header, I think I'll just have to
disable this functionality entirely for the info header.

You're right that users can't throw the split over to one side with reckless
abandon anymore, but they can still easily position it at header height + 2
pixels. I think the new, easy way to clear splits will win them over.

[Vino, 2012-06-05 23:58:17]

On 2012/06/05 23:55:39, Vino wrote:

To address the issue Brecht mentioned where users may want to drag an editor to
the size of the header I've included in this latest patch a feature where
holding the CTRL key disables the ability to drag areas closed. This patch also
now disallows dragging closed the info area, most users probably never want to
close that.

[brechtvl, 2012-06-06 12:52:00]

Checking for the info window does not really address the issue. If you drag in
that situation, some screen state ends up wrong, in this case with the outliner
header that gets hidden. That can still happen with other spaces types.

[Vino, 2012-06-06 17:51:00]

Maybe I'm not sure what you mean, then.

Are you talking about how if there's a three areas in a T-shape, and you drag
the top one down to close both bottom areas, Blender won't allow it? That's the
behavior since before I did this patch. If you right click on the horizontal
separator in this example and choose "Join area" nothing happens. I decided not
to fix this issue in this patch, what ends up happening is that the dragged edge
snaps back to header size if it's a T-shape.

Or perhaps you're encountering some other problem that I haven't seen yet? Could
you describe more carefully and/or screenshot/video?

[brechtvl, 2012-06-06 19:50:34]

Steps to redo with latest patch:
* Load factory settings
* Change top info space type to another type
* Drag up separator between 3d view and this space to collapse it, and release
* Afterwards, the space is not collapsed and the outliner header on the right is
partially hidden until it refreshes when you mouse over the outliner.

[Vino, 2012-06-07 21:12:38]

Okay I see it now. This is similar to what I mentioned before, and I think it
has the same root cause. It's a limitation that existed in Blender since before
this patch. T-shaped splits may not be collapsed. In this case, the outliner or
the 3D view must first be collapsed before the header can be collapsed. Since in
the default screen there are two areas in each column (3d/timeline,
outliner/properties) these must be collapsed before the outliner can be
collapsed. In other words, it's not possible to collapse two areas at once.

Since this is an existing limitation from before this patch, I have two options:

* I can add to this patch the ability to collapse multiple areas at once.
* I can fix the display-related problems and not address the underlying issues.
If I do this then the user won't be able to move an area past the header height
if there's a T-shape.

Which do you recommend?

[brechtvl, 2012-06-08 15:18:05]

It's your choice, it would be nice if collapsing worked in this case too, but
don't think it's a requirement for this patch. It just needs to work stable.

[Vino, 2012-06-11 22:22:40]

I chose to do it the simple way for now. I've added the multiple areas problem
to my to do list and I'll handle it at a later time, when I can focus on making
it work for more than just this feature, but also the right-click method and the
drag-handle method. Until then, users can't drag splits with multiple areas on
either side closed, and the behavior in that case remains the same as it was
before.