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Python custom GUI

I googled and search stackoverflow before asking this question
Answers that I don't expect:
wxWidgets is the best Python GUIUse TkInter (BIM) for GUI development.
Q. How to make a GUI without using any module/library? i.e make a GUI from scratch. Modules like tkinter not allowed.

I've made several GUIs from scratch using SDL which is a low level drawing library. The advantage of doing that is that it will look exactly the same on any platform down to the pixel and you can get it to work on embedded systems. Full screen GUIs are really easy too. Disadvantages are that it is a lot of work.
In python the pygame library wraps SDL so you would use that, and in fact that is how I made the GUI for a lab instrument which had a large colour LCD screen. The controller ran linux, but not X-windows.
pygame is an extra library, yes, but I can't think of a way of making a GUI with only what python provides.

The easiest GUI to make without "module/library" is a web-based one. I.e. generate HTML with Javascript from your Python code, and let the Javascript interact via AJAX with your Python app. This can be implemented without too much effort with just the standard Python library (and some JS code, of course), or with modules that don't require "heavy" installation of platform-specific extensions.

Capturing images from a camera in Python: easy, reliable, cross-platform

What is the most suitable way to capture a still image from Python and convert to a PIL image?
Google gives me numerous ways with OpenCV and lesser-known libraries. I want an easy, reliable, mature, cross-platform library for this purpose. And with minimal dependencies and extra packages.
If possible, it must also support displaying live images with major windowing toolkits, although the performance (frame rate, clarity) is not important.

I use gphoto2 and with subprocess. But it should be possible to access this library from ctypes, if you prefer this.

OpenCV's Python API is pretty solid at this point, and OpenCV is easily installed on all major platforms. It's good, and it's probably your best bet. Getting a live feed from a webcam can be done in as little as 10 lines of code.
PIL or its newer fork Pillow are also good, mature, and cross platform.
PyGame also has a camera module, an intro is here: http://www.pygame.org/docs/tut/camera/CameraIntro.html but I have noticed that getting PyGame to integrate gracefully into other toolkits (wx, Qt) can be difficult.

Writing a lockscreen for Linux?

I've been looking around for a nice lockscreen to use with my XFCE system, but it seems like there are any slim lock screens around. I'm currently using slock, but it's just a blank screen with absolutely no interface whatsoever.
I'm looking to code a lockscreen in Python. I looked at the source code for slock, and it seems like I have to interface with Xorg somehow.
Does anybody know anything about writing lockscreens?

If you want to go low-level, you can use python xcb bindings.
If you want to use higher level bindings, you may find this tutorial on writing a screen saver with Qt useful. Porting it to PyQt should be quite straightforward. I'm pretty sure similar resources exist for GTK.

Best way to build a cross-platform and custom-skinned application with Python

Features needed:
A framework, allowing me to build tab-based application with custom design (like in Hotot twitter client), keeping the native os window frame.
Compatible with Python.
My application will be running under Win/OsX/Linux/.
No Flash/Flex/AIR.
I also would like to ask if PySide does meet my requirements and is it worse or better than wxPython and Tkinter mentioned already?

Use Tkinter. It works on every platform that Python supports, is relatively easy to program in, looks pretty good on most platforms, and has the features you want. It's also built-in for most versions of Python, so your users (in many cases) will not have to install any external dependencies.
I find that Tkinter looks best on Mac OSX and Windows, and slightly outdated on some Gnome desktops. The most important feature, however, is that the API is extremely clean and easy to use and it is very lightweight. PyQt has a similar feature set, but, in my experience, its performance is significantly degraded when compared to Tkinter.
PySide is Nokia's Qt binding for Python. I'm not aware of what the differences are between it and PyQt. Ultimately, most GUI toolkits for Python are going to be cross platform and support the functionality you need. I suggest Tkinter because I feel it is the easiest and most pleasurable way to program GUI applications in Python.

I am the author of Hotot.
according to your requirements, the key for you to choose a framework is the UI framework should be able to access webview conveniently.
Hotot has several wrappers for different platforms. On Linux, we have both Qt and GTK version, on Windows, we provide a Qt version, on Mac, we have a Cocoa version, and of course we have a Chrome version. In a word, all they can easily access webkit.
PS: XULRunner is another good choice for native appearance.

Additionally to the advices given by other people, I suggest you to use PyQt which is a Python binding to Qt framework. It's widely used, cross-platform and feature-full.

Take a look at wxPython (based on wxWidgets). If you want to make it web-based, look into using Django.

Well, you mentioned PyHotOt, and it says (on its web site) that it uses pywebkitgtk, and PyGTK. PyGTK/PyWebKitGTK exists for windows. Did you check it out? I think OS X would be the weak link on GTK, but maybe it's pretty good too.

OpenGl with Python

I am currently in a course that is using OpenGL and I have been using C for all the programs so far. I have Python installed on Fedora as well as OpenGL, however the minute I call an OpenGL command in my Python code, I get a segmentation fault. I have no idea why this is.
Just to avoid the "just use C" comments, here is why I want to use Python:
There are a couple reasons I am wanting to switch from C to Python, but the main one is because we are about to start writing a raytracer and I would like to use classes to make it easier on me. Since I hate classes in C++ and structs in C seems a little crazy, I thought I would give Python a try at it. I have also been looking for a reason to use Python again as it has been a while.
Thanks for any help.

You may also want to consider using Pyglet instead of PyOpenGL. It's a ctypes-wrapper around the native OpenGL libs on the local platform, along with windowing support (should handle most of the stuff you want to use GLUT for.) The pyglet-users list is pretty active and very helpful.

Well, I don't know if these are the libs the original poster are using but I saw identical issues in a pet project I'm working on (Graphics Engine using C++ and Python) using PyOpenGL.
PyOpenGL didn't correctly pick up the rendering context if it was created after the python script had been loaded (I was loading the script first, then calling Python methods in it from my C++ code).
The problem doesn't appear if you initialize the display and create the OpenGL rendering context before loading the Python script.

What OpenGL library are you using? What windowing library? What version of Python?
Most likely cause I can think of is that your windowing library (SDL or whatever you're using) isn't initializing OpenGL before you start calling into it.

We have neither ideas about random segmentation faults. There is not enough information. What python libraries are you using for opengl? How do you use them? Can you show us your code? It's probably something trivial but my god -skill ends up to telling me just and only that.
Raytracer in python? I'd prefer just doing that in C with those structs. But then, I'm assuming you aren't going to do a realtime raytracer so that may be ok.

Perhaps you are calling an OpenGL function that requires an active OpenGL context, without having one? That shouldn't necessarily crash, but I guess it might. How to set up such a context depends on the platform, and it's been a while since I used GL from Python (and when I did, I also used GTK+ which complicates matters).

Scripts never cause segmentation faults.
But first see if your kernel and kmod video driver working property ...
Extension modules can cause "segmentation fault".