#!/usr/bin/env wish
ttk::label .cnt -textvariable cnt
ttk::entry .input -textvariable cnt -validate all \
    -validatecommand {string is integer %P}
ttk::button .inc -text +1 -command {incr cnt}
ttk::button .dec -text -1 -command {incr cnt -1}

grid .dec .cnt .inc
grid .input - -