Configuring the CentOS 6 GNOME Desktop Panels

The CentOS 6 GNOME Desktop Panels are one of the most useful aspects of the desktop in terms of providing information, ease of use and convenience to the user. As with just about every other aspect of the GNOME desktop, these panels are accompanied by extensive configuration options. In this chapter we will look at each of these configuration options in detail.

On a newly installed CentOS 6 system there are two panels configured by default. These appear at the top and bottom of the desktop respectively. The top panel contains the main desktop menus and a number of status areas with information such as the system time and audio settings:

The bottom panel contains the trash can, access to the various virtual workspaces and also has a button representing each application currently running in the current workspace.

These panels can be configured in a variety of ways including:

• Adding additional panels to the desktop
• Moving the panels to different locations on the desktop
• Adding mini applications (such as stock ticker, system monitor or weather applets) to a panel
• Size, background, visibility and transparency of each panel

In the remainder of this chapter we will look at each of these customization options in detail.

A panel may be placed in one of four different locations on the desktop: the top, bottom, far left or far right of the desktop. The location of the panel can be adjusted using the Properties dialog of the panel. This dialog is accessed by clicking with the right hand mouse button on any blank area of the panel and selecting Properties from the popup menu:

From the Panel Properties dialog, change the Orientation setting to the desired value to position the panel as required.

New panels may be added to the desktop by right clicking on any existing panel and selecting New Panel from the resulting menu. The new panel will be placed in an orientation where no panel currently exists. If you already have panels on all four sides of your desktop, the new panel will be placed next to a pre-existing panel. It is possible to fill your entire desktop with panels if you wish, though it is hard to imagine a situation where this would be desirable.

An existing panel may be removed from the desktop by right clicking on the panel and selecting Delete This Panel from the popup menu.

A number of configuration options are available for changing the appearance of each desktop panel. These changes are implemented using the Panel Properties dialog (accessed by right clicking on the panel to be changed and selecting Properties from the popup menu).

The Size property controls the height (when the panel is in a horizontal orientation) or width (when in vertical orientation). It is not possible to reduce the size to the extent where items will no longer be visible (the minimum value is typically around 23 pixels). A different color or even an image may be specified for the panel background. These settings are available from the Background page of the panel properties dialog:

The level of transparency may be specified by selecting the Solid color option and adjusting the Style slider.

The panel may be further configured so that it remains hidden until the mouse pointer moves to the side of the desktop where the panel is located. To activate this feature, select the Autohide option on the General panel of the properties window.

Finally, if you do not wish to have the panel occupy the full width or height of the desktop (depending on the orientation of the selected panel), unset the Expand option. The panel will then only appear as wide or as tall as it needs to be to accommodate the items it is configured to display.

When CentOS 6 is first installed, a number of items are added by default to the two panels. Additional items, however, may easily be added to any panel. There are a couple of ways to add items to the panel.

If there is an application you frequently launch from the Applications menu there is a quick way to add a launch icon to the panel. Simply open the Applications menu and navigate to the menu option for the desired application. Rather than clicking on this menu item with the left mouse button as you normally would, click instead with the right mouse button and select the Add this launcher to panel option. An icon representing the application will subsequently appear on the panel which, when clicked, will launch the corresponding application.

Alternatively, launch the Add to Panel dialog by right clicking on a blank area of the desired panel and selecting Add to Panel… from the resulting menu. In the resulting dialog select Application Launcher… and click Forward. The dialog will list each menu item and all sub-menu items. If, for example, you wanted to be able to launch the Terminal window from the panel simply click on the arrow next to System Tools in the Add to Panel dialog to unfold the list of System Tool applications. Scroll down the list, select Terminal and click on the Add button:

In addition to applications from the menu, it is also possible to add a range of items specifically designed to appear on panels. To add such items to a panel click with the right mouse button over the panel to be configured and select the Add to Panel menu option from the resulting popup menu. The Add to Panel dialog will then appear as follows:

To add an item to the panel, simply scroll through the list provided, select the required item and press the Add button. The following CentOS 6 desktop panel includes the System Monitor and Invest items:

To edit the properties or preferences for a panel item, move the mouse pointer over the item in the panel and click the right mouse button. Select either Properties or Preferences from the menu and the appropriate dialog will appear. For example, the Preferences panel for the Weather Report item allows various settings to be changed, such as the geographical location and units for displaying temperature (Celsius or Fahrenheit). The system monitor can similarly be configured to also display metrics such as system load, memory and network usage.

To delete an item from a panel right click with the mouse on the item and select Remove from Panel.

To move an item to a different location in a panel right click with the mouse on the item and select Move. Then use the mouse to drag and drop the item to a new location. Alternatively, click with either the middle mouse button, or the left and right mouse buttons simultaneously and drag and drop the panel item to the new location.

To add an application not currently available from the desktop menus simply select the Custom Application Launcher, click Add and specify the path to the application executable and provide a name. Click on the No icon button to select an icon to represent the item on the panel.

Any of the sub-menus in the Applications, Places or System menus may be added as icons to the main panel. To add, for example, an icon to access the Application -> Accessories menu to the panel, open the Applications menu and right click on any item in the Accessories menu item. From the popup menu, select the Entire menu... option followed by Add this as menu to panel. An icon will then appear on the panel which, when clicked, drops down the Accessories menu:

Alternatively, the menu may be added to the panel as a Drawer by selecting the Add this as drawer to panel menu option. A drawer is similar to the menu with the exception that only the icons are displayed and an Up arrow button is used to close the drawer:

The CentOS 6 GNOME desktop supports multiple desktop workspaces (these are essentially individual screens which the user can switch between to avoid having to have all applications cluttered onto one screen). Switching between workspaces is achieved by clicking on the workspaces in the bottom desktop panel. The image below shows a section of the panel from a desktop with two workspaces (the default for a new CentoS 6 installation):

To increase the number of available workspaces, right click with the mouse on the workspace control (as shown above) in the panel and select Preferences. Simply increase the Number of workspaces value to the desired number. The name of each workspace may be changed by double clicking on the default name in the list (Workspace 1, Workspace 2 etc) and typing in a new name.