The program now is able to find the layers count in the gcode file (for Simplify3D and Cura) and show a message when the program selected is wrong.
Also, the layer number is displayed to the user in the label, and the maximum layer number to choose in the spinbox is fixed to the number of layers in the gcode file.
Conected slots and signals, created functions for save, browse and export buttons. Also, created the first script to look for the keyword layer in the file.