Projects/Plasma/FAQ

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Projects/Plasma/FAQ


Introduction

Plasma is one of the key technologies of KDE 4 (also known as the "Pillars of KDE"), and one of the most visible to users. As Plasma treats the user interface differently than a traditional desktop, there may be confusion on what Plasma is, what it does, and how to perform common tasks.

This document attempts to address these problems by providing answers to the most common questions.

General Questions

What does Plasma do?

Plasma is the component that is "in charge" of the desktop interface; the desktop, panel (often referred simply as the task bar), and related elements. However, Plasma goes a bit further than these common pieces to the interface puzzle. The "Desktop" has not changed much since originally conceived; it typically consists of shortcuts, a panel, and icons for currently running applications. Plasma aims to change that, incorporating semantic application elements, and bringing cooperating technologies to the user's fingertips in a way that is visually appealing while easing work flow.

What is wrong with the current desktop technology?

Today's desktops are static. Typically they are tied to a folder in which one can find icons (application launchers), or user-placed documents and folders. Along with pictures and images as backgrounds, the current desktop doesn't go any further, or work for the user. Plasma takes a different approach, engaging the user by creating a dynamic and highly customizable environment.

I don't think it's such a good idea...

With Plasma, you can let your desktop (and accompanying support elements) act like it always did. You can have a task bar, a background image, shortcuts, etc. If you want to, however, you can use tools provided by Plasma to take your experience further, letting your desktop take shape based on what you want and need.

How does Plasma work?

Plasma's components are widgets called Plasmoids. Plasmoids can take on a variety of functions, ranging from displaying your desktop and associated wallpaper, showing your laptop's battery level, displaying your plugged in devices, and drawing the taskbar. Widgets can be grouped together in "containers" called containments.

It doesn't sound too new... other operating systems have done that.

The key difference here is that plasmoids can interact together. You want a better view of your laptop battery in order to find out when you are running low? You just drag it away from the taskbar and put it on the desktop. Also, applets can be resized and rotated at will, thanks to the use of Scalable Vector Graphics (SVGs). As you can see, the desktop not only interacts with you, as the user, but also with itself in new and interesting ways. You are now able to control how your workspace behaves and what it displays, in a visually pleasing and user-friendly manner. Since Plasma is the sum of its plasmoids, every element, even the desktop itself, is a widget. This allows you to move your desktop anywhere with respect to the windows (back and forward). It is no longer rooted behind everything and becomes instead another element of real interaction.

Kicker and Kdesktop were working fine in KDE 3! Why did you have to change that?

Especially regarding kicker, there was the important issue of maintainability. The code was in place since the KDE 2 days, and it was difficult to add new features without breaking others. In the end, to proceed forward the only viable option was to start anew from scratch.

I can't find my favorite <insert feature here>!

Don't forget that Plasma is still in its infancy (it's brand new, after all) and that KDE 3 was an extremely polished codebase: it took seven years to get to that, while Plasma had about 18 months to get to its current status. With time, the Plasma developers plan on reintroducing features that are missing and fix regressions. As KDE progresses through the KDE4 cycle, Plasma will improve with it.

Why on earth did you decide to change the way the desktop operates?

The idea of a Desktop folder is fundamentally a broken concept. It assumes that everything you will access there resides on a single physical directory on your disk. It may be convenient, but at the same time it greatly limits what you can do. For example, you can't use custom layouts for different desktops, as everything would be read from the directory. Also, quite often a desktop structured like that becomes a dumping ground for files and folders, without any other function. That said, you can have icons on the desktop in Plasma.

What's the deal with the K menu? It's big and ugly!

During the development of KDE 4.0, different approaches for a K menu (application launcher) were tried. Some projects, like Raptor, were ambitious but there was no way they could be completed on time. At the time, one developer ported SUSE Linux's application launcher (Kickoff) to the new KDE architecture. As it was the most ready and feature complete (not to mention the product of usability testing) it was chosen to be the default menu in KDE 4.0. However, this does not mean that there aren't alternatives: projects such as the aforementioned Raptor or Lancelot are being actively developed. There is also a "traditional" K-menu available.

What is the Zooming User Interface (ZUI)?

The Zooming User Interface, or ZUI, is another component of Plasma. It enables the user to group different groups of plasmoids together, and to quickly switch between one and another using a zoom-and-pan approach. Notice that at the time of writing this feature is still under heavy development and may be fully functional only with later KDE 4.x releases.

How does the ZUI work?

Suppose you have three groups of plasmoids (such as widgets, application launchers, etc.) which you want arranged in specific combinations depending on what you want to do. You first group them according to your tastes, then you can switch between them by zooming out (getting a preview of all the groups) and then back in on the specific group you want to use. Notice that it is different from traditional X11 virtual desktop switching, as there is a higher degree of flexibility by using this approach, as the groups can be totally different from each other.

Configuration

Can I place icons on the desktop?

Of course you can. Dragging an icon from Dolphin or Konqueror to the desktop will work. There is also legacy support for the existing Desktop folders, which means that the contents of your existing Desktop folder will be automatically displayed.

I am using two screens, and I used to have kicker over the two displays. Can I do that with Plasma?

No. The reason is that having a panel over two displays adds a great deal of complexity, especially when the two displays have different resolution. As a result of this added complexity, this feature would not be guaranteed to work in all cases. As a result it was not implemented.

How can I add applets to the panel?

Open the Add Widgets dialog in the Plasma toolbox (upper right corner of the screen) then select the widget of your liking and drag it directly (don't double click or use the Add Widget button) to the panel. It should embed gracefully. If it doesn't, there is probably some bug in the widget itself.

I heard that you can use OS X's widgets with Plasma. Is this true?

There is some code in place already, however as widgets rely on WebKit, it won't be available until Qt 4.4 (which incorporates it), and therefore unlikely before KDE 4.1.

My widgets are hidden under the windows. How can I show them?

You can bring all the widgets to the front by pushing Ctrl-F12, which will bring the Plasma Dashboard to the front.

How can I lock the positions of the widgets?

Right click on an empty area of the desktop and select "Lock Widgets" from the contextual menu. If you want to reverse that, right click again and select "Unlock Widgets".

How do I remove widgets?

If they're on the panel, right click on the widget and select "Remove this...". If the widgets are on the desktop, you have different options:

  • If you hover over them, clicking the red X will remove them;
  • If you use the Add Widget dialog, you can click on the minus symbol icon next to the widget name to remove it.

How can I change the height of the panel?

In KDE 4.1 and later you just need to right-click on the Panel, select "Panel Settings" and then choose whatever size you would like to have.

In KDE 4.0.2 you are able to change the height by editing a configuration file by hand. A graphical option could not be introduced due to some restrictions in effect for 4.0.x releases (namely, the feature freeze and the string freeze, the latter not allowing new translatable strings to be added).

Notice: Plasma must not be running when you attempt this, otherwise it will overwrite your settings. So, first of all, quit plasma:

kquitapp plasma

As a second step, open $KDEHOME/share/config/plasma-appletsrc with a text editor of your choice. Locate the line which says "plugin=panel" and add a line with the preferred height of the panel in pixels (e.g., size=24 will give a panel 24 pixels high). Save the modified file and start Plasma again.

Theming

I don't like the default look of the panel and other Plasma components. Can I change that?

Yes, the ability to change the look of Plasma was planned since the beginning. Plasma can use "themes", which are essentially a number of SVG images and files specifying the colors, to change its appearance. Some themes have already appeared on popular sites like kde-look.org.

Is there a GUI option available to change the theme?

Not yet, but it is planned for the future.

I still want to change the theme! What do I do?

First of all, obtain a theme (kde-look.org is a good place to look). The second, important point is that Plasma must not be running when you make the modifications or they will be overwritten. So you must quit it before with:

kquitapp plasma

Notice that doing so will also kill the desktop until Plasma is restarted, so keep a terminal window (for example Konsole) open while you do the editing in order to restart Plasma after you're done. Then, create the $KDEHOME/share/apps/desktoptheme (where $KDEHOME is the name of your .kde or .kde4 directory, depending on your installation) directory and unpack the theme there. After that is done, edit $KDEHOME/share/config/plasmarc (make a backup copy just in case) and locate the section named "[Theme]". Change "default" to the name of your downloaded theme (see instructions from the theme's author) and then start Plasma:

plasma

Troubleshooting

My panel is gone, how do I get it back?

kquitapp plasma; rm $KDEHOME/share/config/plasma-appletsrc; plasma

This deletes your plasma settings, so you'll get the default configuration back. The panel-vanishing-on-crash issue was fixed just after 4.0.0's release. If running all the 3 commands at once doesn't work, try typing them in manually and wait a few seconds before running the next command.

Some GTK+ applications (such as the IM client Pidgin) do not behave well in Plasma.

That is unfortunately a bug in the GTK+ graphics toolkit which is exposed by the way Plasma operates. A bug report has been opened in the GTK+ bug tracker. Recently, a patch for Plasma (KDE 4.0.0) has been posted in KDE bug tracker and it has also been incorporated in the 4.0 branch (meaning it will be present in KDE 4.0.1).

I use the NVIDIA binary driver on Linux and scrolling is really slow! Is it a fault of Plasma?

No, it is a bug in the NVIDIA binary driver. Update the driver to version 169.07 or newer and the problem should be solved.

Glossary

  • Containment: A container for different plasmoids. The desktop and the panel are examples of containments.
  • Panel: The place where the K-menu, taskbar, system tray and other componenents reside. Often called taskbar.
  • Plasmoid: A component of Plasma. Often referred as widget, or applet.

Thanks

Daniel Laidig & Simon St.James - thanks for the umeet IRC logs!

Contributors

TODO

  • Write a glossary
  • Better grouping for the questions

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