Software installation and startup

Installation

ROX applications should be distributed as application directories. An application directory contains all the resources that a program needs (source code, binary, images, help, etc) in a form that can be used directly without the need for any installation.
They must be relocatable at run-time, so don't put any absolute paths into your programs (ie, don't assume the application lives in /usr/local/apps, etc). Don't assume the user installing the software has root access.
ROX applications should not normally be supplied with any kind of installer. This makes software installation simpler and easier for everyone, and completely automatic for Zero Install users.

There are a few cases where you might want to install shared resources. Some of these are examined here:

Icons for filetypes

It is the user's choice what icon to use to represent each type of file. You should only set the icon for a file type if there isn't one set up already, and this should be done when the program is run, not when it is installed.
When your program is run, if <Choices>/MIME-icons/type.png is missing (or a broken symlink) then you may symlink it to an icon inside your application.
Note that we support freedesktop.org's icon theme spec in the CVS version of the filer. In that case, install your icon as mime-application:foo into the default theme (hicolor). This will make it visible to other desktops, too (support for this may take a while to catch up).
Packagers for distributions may choose to set a system-wide icon when the package is installed; this must be coordinated over the whole distribution to avoid conflicts.

MIME-info rules (guessing a file's MIME type from its name)

Like icons, MIME-info rules should be installed at run-time. Drop an XML file with your program's name into the shared MIME package directory (see freedesktop.org) and
run update-mime-database.

MIME-types (what application handles each type of file)

ROX-Filer provides a very easy way for users to specify which application should handle a particular type of file. Do not set this yourself.

Services

Programs which should be run automatically on startup should also not set themselves up at install time. You may ask the user if it's OK to be run automatically when they run the program. This allows users to install software without worrying about opening security holes.

As you can see, all these rules mean that you should never have to preform any actions at install time.

Start-up

A ROX application is started by clicking on its application directory, which runs the file AppRun inside. Users will not normally be able to pass flags to your program (although they can give arguments by dragging files onto it).
When run, your program should give the user visual feedback that it is loading. Try to open the main window as soon as possible, even if it appears blank at first. This allows the user to move their eyes to the area where the content is going to appear. It also means they can reposition the window while the program is loading to get it where they want it.
Splash screens may be placed inside the main window -- do not use separate windows or set override-redirect because the user may want to continue working while the program loads.
A better solution than a splash screen is to simply load quickly in the first place! If your program takes a long time to load, see if you can defer some of the initialisation until later.
For example, ROX-Filer only builds the Options window when it is opened, not when the filer is loaded, and it will open a directory viewer before it has finished scanning the directory.