The decompiler has a configuration file. It is installed into the 'cfg' subdirectory of the IDA installation. The configuration file is named 'hexrays.cfg'. It is a simple text file, which can be edited to your taste. Currently the following keywords are defined:
Background color of local type declarations. Currently this color is not used.
Default: default background of the disassembly view
Background color of local variable declarations. It is specified as a hexadecimal number 0xBBGGRR where BB is the blue component, GG is the green component, and RR is the red component. Color -1 means the default background color (usually white).
Default: default background of the disassembly view
Background color of the function body. It is specified the same way as VARDECL_BGCOLOR.
Default: default background of the disassembly view
Number of spaces to use for block indentations.
Default: 2
The position to start indented comments.
Default: 64
As soon as the line length approaches this value, the decompiler will try to split it. However, it some cases the line length might be bigger.
Default: 120