Is there any way to inherit a lexer dynamically?

[runsun]

Suppose we have a lexer A, and I want to make a lexer A2 that has 2 parts:

part1 comes from A
part2 newly added in A2

This A2 has a link to A, so when A is modified, the part1 of A2 is automatically updated.

Is it possible to do this ?

[Alexey]

Sublexers tab of dialog--example is C# which uses xml, C++ uses Asm