handler when exit from a recursive called eventloop
* ext/tk/lib/tk/timer.rb: new TkRTTimer class, which can works for a
realtime operation
* ext/tk/sample/tkrttimer.rb: sample of TkRTTimer class
* ext/tk/lib/tk/textmark.rb: move TkTextMark#+ and TkTextMark#- to
TkText::IndexModMethods
* ext/tk/lib/tk/text.rb: improve TkTextMark#+ and TkTextMark#-, and
add them to TkText::IndexModMethods module
* ext/tk/sample/tktextio.rb: add test part of "seek by text index
modifiers"
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8@8135 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
