examples : fix bug with C > 0 > . > 0 > 0 > 0 > 0 > 1

Signed-off-by: Romain Chanoir <chanoir.romain@courrier.uqam.ca>
examples : adds the disabling  of "." button in calculator

Signed-off-by: Romain Chanoir <chanoir.romain@courrier.uqam.ca>
gitk3_4 : Adds methods "set_sensitive" and "get_sensitive" to gtk

Signed-off-by: Romain Chanoir <chanoir.romain@courrier.uqam.ca>