// ----------------------------------------------------------------------------
// (background) log window: this class forwards all log messages to the log
// target which was active when it was instantiated, but also collects them
// ----------------------------------------------------------------------------
// (background) log window: this class forwards all log messages to the log
// target which was active when it was instantiated, but also collects them
// close it, clear the log contents or save it to the file.
// ----------------------------------------------------------------------------
// close it, clear the log contents or save it to the file.
// ----------------------------------------------------------------------------
// called if the user closes the window interactively, will not be
// called if it is destroyed for another reason (such as when program
// exits) - return true from here to allow the frame to close, false
// called if the user closes the window interactively, will not be
// called if it is destroyed for another reason (such as when program
// exits) - return true from here to allow the frame to close, false