MirAL needs to grow based on feeback on what shell developers really need. The simple miral-shell example is around the "minimally viable product" point. That is, it can be used but isn't very satisfying. Also the encapsulation provided by libmiral is leaky.
ABI design and stability
There are some aspects of the current interface that are of concern for the stability of the ABI. In particular, classes with accessible data members or with virtual function tables can only be modified in restricted ways.
- There are neither tests of MirAL code, nor of the sample code using it. (This comes from its origin as a proof-of-concept "spike", but needs correcting.) The test doubles supplied by mir-test-tools should be helpful. (NB the version of mir-test-tools in Xenial is broken. lp:1583536)
- There's a lack of documentation of the preconditions and postconditions of the API.
Missing functionality
To make use of miral-shell more satisfying there are a lot of pieces of work needed. Some are simple improvements to the sample shell, other may need additions to libmiral to expose additional Mir functionality.
- Titlebars. The default "titlebar" window management strategy paints grey rectangles for titlebars. They should contain the window title and sizing controls.
- Titlebars. The "tiling" window does not offer them at all.
- Titlebars. GTK+ apps provide their own titlebars, better integration is needed.
- Keyboard layouts. It should be possible to configure and use non-US keyboard layouts.
- Better integration of startup animation. A short animation is played on startup. Ideally this should remain visible until a client is launched, fade out over the top of the client and resume when the last client exits.
- launching external clients. There's currently an option to launch e.g. the gnome-terminal at startup. This would be better with Ctrl-Alt-T. But note, forking from a running server (with multiple threads and owning system resources) is a Bad Idea(tm).
- Wallpaper. The default black background is boring.
- Shadows, animations and other "effects".
- Menu integration with toolkits. We should probably support dbus menus.
- Add virtual workspaces. A virtual workspace represents a group of windows that can be switched away from (hidden) or to (shown) in a single action. Each window belongs in a single virtual workspace. A virtual workspace represents a group of windows that can be switched away from (hidden) or to (shown) in a single action. Each window belongs in a single virtual workspace.
- Compositing effects. There needs to be an API for coding "effects" within the compositor (spreads, wobbly windows, shadows).
- Customizing compositing. There needs to be a mechanism for loading custom compositing effects. E.g. specifying a module (or modules) to load.
- Enabling (disabling) cursor when pointing devices are (not) present.
- ability to track connected input devices
- ability to control cursor visibility
- Cursor images. lp:qtmir stubs the cursor images and paints the cursor in its compositor. Need to consider what ought to be supported here.
- Cut&Paste/Drag&Drop toolkits expect this functionality, but it isn't provided by Mir. We ought to find a way to provide this.
The tiling window management strategy
This code was originally written to prove that different strategies are possible, without much consideration of being useful. Here are some suggestions for a better approach:
- top level windows ought to fill the tile when created
- the tiling algorithm ought to lay windows out as follows:
- Single window: takes up the whole screen
- Two windows: The screen is split in two tiles of equal width (half the screen’s width) and full height. Each window is placed in a tile (left or right), with the newest window occupying the left tile.
- Three or more windows: The screen is split in two tiles of equal width and full height, as in the previous case. The newest window occupies the left tile. The right part is now further divided vertically into smaller tiles having equal height, to host the remaining windows, with older windows being closer to the bottom.
- Add a titlebar to the top of the screen. The titlebar should be split evenly into horizontal blocks, one per tile. Each block containing the title of the top-level window. The focussed tile is highlighted. Clicking on a title selects the corresponding window.
Art Resource
Anyone who is able to create and propose some examples to then pick from. We currently need:
- Default wallpaper
- Default icon (using ubuntu logo atm). Must be svg