Qt/Gtkmm/wxWidgets/TclTk which free framework is more suitable for commercial low power Linux based embedded systems?

Question

Python

Any framework will allow not to provide source codes?
Is it legal to hide part of the code in dynamic libraries, and open only part of the code using open libraries?
Does the license of the free Qt Creater allow it to be commercially used for an embedded device?
Which framework will be cheaper to use if you need to hide the source code?
Is it legal to deny a buyer access to an embedded Linux system? To exclude incorrect control of the device for the warranty period (when it is necessary to repair for free).

Answer 1

Qt seems to be the most expensive solution and probably illegal for devices to use for free.
GTK - seems to be open source only.
wxWidgets - seems to provide free use in closed applications, but no Linux is built on it, apparently not only the appearance is bad, but also the performance
CPPTK library for Tcl / Tk - since 2006 is not supported and with an unknown license . you need to contact the author personally), although Tcl / Tk is built into Python by default.