Once data have been imported/opened in GCLAS and the GCLAS year created, you'll see a multi-panel display showing the data in both graphical and tabular formats. As a new user of GCLAS, you'll be confronted by two challenges: (1) learning the functions of all parts of the main GCLAS window and (2) learning to manipulate the various panels within the window, which differ slightly from other windows-type interfaces you may be familiar with. This section tackles both challenges in turn. We advise you to read this section carefully while looking back frequently at the initial layout of the main window (do this before you resizing or repositioning panels). This will help prevent your hiding one panel behind another and the attendant frustration of searching for missing items. We also suggest that you maximize the GCLAS window to fit the whole monitor screen for the best view of all the GCLAS parts.
Initially, seven panels are displayed in the main window. In addition, a window labeled Ref. curves (Transport) is minimized and shows as a small rectangle in the lower left corner of the main window.
The upper third of the main window contains two panels:
(top tab) shows the files that you've loaded into GCLAS and the
folders that they're stored in and allows you to pick and choose the data to display and work on. The graph
view 
(middle tab) shows an overview
graph of your time-series data. The ancillary information view 
(bottom tab), when fully operational, will provide miscellaneous
information about the GCLAS year being worked.
The middle third of the main window contains three panels:
An alternative configuration of the preceding three panels is available by pressing the panel orientation button
in the upper right corner of the working graph panel. Pressing this button changes the orientation of the working graph and tabular data panels from side-by-side to vertically stacked. (Note: This arrangement hides a couple of the panels, so don't try it until you're used to doing basic manipulation of the panels.) The many tools and functions available in these panels are discussed in Adding and Editing Concentration Data.
The bottom third of the main window, which is used for computing and applying cross-section coefficients and computing loads, contains two panels whose functions change, depending on which of the tabbed folder views (Calculate Coefficients, Apply Coefficients, or Compute Loads) has been selected. Details about this panel are given in Analyzing and Applying Cross-section Coefficients and Computing Loads.
When maximized, the transport relation window (shown above) shows a scatterplot of concentration as a function of flow for the non-estimated concentration data in the input data set, and it can be used to help you estimate and fill in missing data. Left click anywhere on the small rectangle to maximize this window; left click in the little square in the upper right corner of the maximized window to minimize it again. Details about this window are given in Using the Transport Relation Window To Aid Estimation.
The GCLAS windows (main window and transport relation window) work pretty much like windows on a PC or UNIX machine. You can, for example, drag them around on your computer screen, and you can minimize them by left clicking on a small box in the upper right corner of the frame.
Panels, however, behave differently. You cannot drag them around the screen like you can windows, but you can resize them in two ways:
Try these features out. If a panel disappears, you've merely slid another panel over top ot it. Just locate the offending panel and resize it. Once you get the hang of the panel arrangement, you'll find that it's convenient to hide unused panels by sliding panels of current interest in front, thereby maximizing your active working space.
Tabs are another important feature of certain GCLAS panels. They look similar to index tabs in a three-ring notebook or on manila folders. You can use tabs to locate and display various views of a multipart panel. Try left clicking on the tabs in the file tree and graph overview panel, the tabular data panel, and the two panels in the bottom third of the screen.
Buttons, which are used to execute common functions, are included at the top or side of some of the panels, and they work much like buttons do in other windowed software.
Details about the functions of individual panels and the tabs and buttons that belong to them are given in other parts of the help manual where the various GCLAS computation capabilities are described, as well as in Quick References.