The plot thickens! Everyone, let's get ready to paint huge banners, with sad triangular arrows in perverse orientations, and shout slogans outside the Ableton HQ!
Poster wrote:And why think of an own convention when there's already one that has been there for years, for a good reason..
There is, most certainly, a GUI convention in which arrow icons are pointing at the actual direction where the expansion is going to take place. In my opinion, that's also the most intuitive one.
All of Live's "Audio From", "Midi From" (and similar) controls still use this logic. There's an arrow down, and you know you're going to get a vertical expansion at that location if you click it. Yep, I know they aren't actual expandable GUI panels per se, as they are menus which appear on top of the other controls - but they demonstrate the logic.
The convention of arrows denoting the direction of the expansion is a very common one, and it's often used in the case of expanding GUI panels being used in multiple directions inside the GUI - just like Live's browser, help info view and the clip/MIDI/chain view. Think about expanding and collapsing web browser panels, think about the Photoshop dock panels, Lightroom view panels, Microsoft Office expanding selection panels, numerous web interfaces - they
all use arrows pointing at the actual direction of the expanding area, and for a good reason. They do this instead of an abstract "if the arrow indicates an arbitrary direction parallel to the current GUI element, there must be something closed over here"
Seriously, if you place expanding elements in your GUI and they are arranged in a uniform fashion, like a vertical column, using the more abstract "directory-tree-like" arrow notation is of course a valid design (think of the left panel of Google Earth, for example). However, when you have stuff expanding like in Live, that is, towards the right from the left, towards the left from the right, upwards from the bottom, upwards from somewhere in the middle, and so on, AND you choose to use the tree-like abstract arrow notation, AND you decide to
rotate the arrows while doing so, to fit what ever relative position you might need...
That's how it is at the moment. I mean, we now have arrows pointing down, right, left, and they all mean "there's stuff collapsed over here, and it's most likely going to expand 90 degrees from the direction of this arrow." I do see the logic and know I'll soon be using it without flinching, but it WILL throw a lot of people off when they first try it.