Nice feedback saulgoode, nightflier! Keep it coming. Here's a few thoughts on it:
I am somewhat confused by the buttons across the top of all of the windows ("Welcome!", "The Choice", "Partitions", etc). I imagine much of their functionality is dictated by Gambas but they seem to violate some of the principles of user interface design. In particular, the outlining of the button for the currently active window. A button is outlined to signify that it is the Default action to be taken if RETURN is pressed, not to indicate the current "tab" in a set of windows. Since the result of clicking on the outlined button in the current setup would be to redisplay the same screen (presumably), it is therefore effectively just a Cancel operation. If the Default operation of a screen is Cancel, all of the HIGs with which I am familiar recommend that no button be outlined.
You're right about that. I actually started with a tabbed interface, but there was no way to disable tabs selectively. I'll think about this and look for alternatives to show which top-row function is currently active.
The Welcome
This looks great and seems very intuitive. My only criticism is the above mentioned issue with the outlined "Welcome!" button. For this screen, it would seem safe to make the "Start" button the Default action and therefore it should be outlined.
Agree. That "Start" button is my most recent addition and makes the "Welcome" screen much more intuitive than before, when you had to click on an enabled "The Choice" button.
The Choice
Almost perfect aside from the Default action. In this case, I would propose there be no Default action as all three of the options are equally valid.
Agree.
Partitions Tool
I personally dislike the "You have been WARNED!" attached to the "Full disk" blurb. It is unnecessary, seems patronizing, and serves as something of a distraction -- the user has just been presented with the suggestion that having multiple disks affects his decision and should be permitted a chance to absorb that concept.
Wasn't my idea and all the texts are subject to change. Can't really make my mind up if I'm for or against it though...
I am presuming that the buttons "GParted", "cfdisk", and "Preset strategies" will fork the process off to another window where those specifications are made. If this is the case then those buttons should have ellipses after the text to indicate this ("GParted...", "cfdisk...", and "Preset strategies..."). I realize that ellipses detract from the "beauty" of the interface but they are something of a standard "hint" for buttons which bring up a dialog for further input.
I came up with a way to embed gparted and cfdisk inside the installer Main window, so it looks like part of it. I didn't want another window popping up on top. I think there are screenshots of this among the original ones on my webpage.
Personally, I think that any external utilities should be hidden from the user (except for "Advanced" installs) and "wrapper" user interfaces consistent with the rest of the GUI install written. I realize that this is extra work but I felt it should be mentioned as the ideal.
Agree. See previous quote.
Packages
Looks good aside from the previously mentioned issues of specifying (or not) a Default action and adding ellipses (in this case, to the "By groups" and "Manual" buttons).
I'll check on this during the overhaul of the button focus matter.
Configure
This window looks good. My only concern would be about "Other configurations": to be symmetrical with "Boot manager", there should be a grouping of buttons for "Config 1", another grouping for "Config 2", et cetera (unless I am misinterpreting those other configurations).
Config 1 and 2 are just placeholders for as yet unthought of configurations...

They will change to something real or go away altogether.
Go for it!
For this window, I assume the install is already in progress and the message "Ready to install" should be updated to say "Installation in progress" or somesuch. If the screen capture is actually showing the program waiting for user input (i.e., actually "ready to install") then there should be a 'proceed' button (or somesuch) underneath the "Ready to install" label.
I haven't even really began work this screen...

This is just a first "sketch" on how it might look.
Tools
Looks good. Even the lack of ellipses could be justified as they might lead to confusion. I would only restate my distaste for the "You have been WARNED!" admonition.
See related reply above.
I don't mean to sound overly negative; I actually think it is a phenomenally good interface design. I also imagine I have misinterpreted what is being presented in some cases and that in others, your designs are so preliminary as to have not yet address some of the aspects I mentioned.
Do't worry about sounding negative and keep the feedback coming. This is actually helping to rekindle my interest on hacking away on the installer, which I'd sort of put on the backburner because of other development tasks. You are correct on "preliminary...

My main point of contention would be the outlining of the header buttons along the top. Hopefully there will be some other way provided by Gambas to signify the "active page"; outlining of a button is already taken. (I don't think a "tabbed" approach would be desirable here, either. Tabs tend to place things on an equal footing whereas your buttons have a "sequence" associated with them.)
See related replies above.
I would think that outlining the buttons are, as saulgoode says, significying the "focus" of the Return Key (and/or Space Bar). This focus can be moved by the Tab Key, to accomodate keyboard users, right? We should keep that.
Food for thought, haven't done any work towards allowing keyboard navigation, as it's better done after the interface is stable, but will keep it in mind.
If there is a way of applying a 3D "depressed" look to the active button it would be ideal.
As mentioned, I'll look into other ways to handle the button focus problem.
Will the user be able to jump back and forth at will using the buttons to change their choices before committing?
That's the idea, but how far that is possible will depend on the choices made along the way.
"Go for it": I agree that needs an action button on the right side, maybe one which changes to "Cancel" after pressing it.
As stated above, I haven't even really began work this screen...
