GUI toolkits with Tkinter's .pack() alternative

[Alex9968]

Hi all,

I use Tkinter's Pack widget geometry manager (I really prefer it over 
using visual GUI designers), so my question is which other GUI toolkits 
have similar functionality.

Secondly, I like the detailed widget borders configuration possible in 
Tkinter, which can be used to tweak GUI look, and wonder if other 
toolkits support it. With Tkinter's case, I like the resulting (tweaked) 
look in Windows, but I'm afraid it can be quite different (and ugly) on 
other platforms.

(The reason I ever consider moving from Tkinter is some inconveniences, 
involving for example window scrolling, plus its smaller amount of 
widgets compared to some other toolkits, plus its (rumored) ugly look on 
certain environments. I will not necessary change the toolkit, but I 
have to consider it)

Could anyone with experience in different toolkits help, please

Thanks