After ObjectLand start a window shown at figure 4-1 is opened . This window remains on the screen until ObjectLand works and that is why it is called the main window.
The main window enables to select for work one of the present GDB (or create a new one), perform some operations with GDB as a whole and the most important – it gives a possibility to browse GDB structure, select its components and work with them and also with components of the shared style library.
Figure 4-1. The main ObjectLand window
The main window reminds the window of the system program “Windows Explorer”. The window title contains the name of the system and the number of its version, and also the name of the current GDB (if any), the current user name (if there is a list of GDB users) and a short name for GDB open mode (if there is a current GDB).
In the left part of the window there is a hierarchical pane containing the structure tree of the current GDB and shared style library, and in the shared access mode – also lists of the current working sessions of users with GDB and shared library. If there is no current GDB the tree contains only “Shared style library” component.
The user can select any component from the structure tree in the left pane. These components can be shown in closed state (icon 
) or in opened state (icon 
). After opening the selected component you can see its structure. Thus, with opened component “Shared style library” we can see that this library is made up of components “Fill styles”, “Line styles” and so on.
The right part of the window is occupied by the list pane which displays elements of components structure selected from the tree. It is possible to select one or several elements in the list pane to work with them (let us remind you that for a multiple selection the key Shift or Ctrl are used). In the status bar, at the bottom of the window, the total number of elements in the right pane and the number of selected elements is indicated.
Double-clicking by the left mouse button on the element from the list pane brings up the execution of some standard action depending on the element type. Usually this action is connected to opening a window for browsing and editing the corresponding GDB component (for example, theme browser window or style editing window). In the cases when for elements of a particular type a browser or editor window is not provided (for example, for table field) a window of element's properties is opened instead.
Operations on moving along the GDB tree structure, browsing different structure components, opening and closing components and so on are usually called navigation in GDB. In this connection the main system window and similar windows are called navigation windows.
