Background Designer

' Background Name' - represent name of the background. The name helps to identify background in the backgrounds list.
'Enable' checkbox - enables or disables modification of picture's background corresponding to the state
'Select Gradient' - shows 'Gradient Designer' window
'Preview' - causes the software to redraw background with applied changes
'Add to Backgrounds' - adds current background to the backgrounds list, assessable by pressing 'View Backgrounds' button.
'Picture Intensity' - changes external picture intensity. The smaller the value the less intense the external picture. Values are in the [0-1] range.
'Picture Mode' - specifies the action, which should be applied to the picture if its dimensions are not equal to the dimensions of the resulting picture. Only Stretch mode works so far.
'File name' - specifies the file name of the external picture. Press '...' (ellispes) button to pick up a file.

The background can contain eight linear lights with intensity, proportional to reciprocal distance to other lights, one gradient and an external picture.

Checkboxes followed by light name shows if current light is enabled, following combo-box represent second colour of the gradient. If the second colour is absent then the colour is considered as a linear light, otherwise - as the gradient.
The position of linear light can be changed by moving corresponding scroll bars.

View of the 'Background Designer' window

Material properties, light model and other properties of scene can be adjusted in this dialog.

This tool helps to create a gradient. There is a number of gradients included in the gradients list.

'Gradient Name' - helps identifying the gradient and represent gradient's name in the list.
'Light' - specifies light type. Linear light makes picture smoother, whereas cubic light makes it flatter.
'Slices' - represents number of divisions in sliced gradients.
'Type' - represents gradient type. 'Uniform' - background area is rectangular with dimensions H and W. 'Sliced' - background area consists of a number of slices. 'Sliced Spherical' - background area is represented as dart board.
'Colour Scale' - specified possible maximum of the 'Expression'.
'Expression' - shows how coordinates are being calculated.
'Start' and 'End' colours represent design only colours. Actual colours are specified in 'Backgrounds designer'

View of the 'Gradient Designer' window