Pros

• First-class Linux framework.
• LGPL
• Nice support for externally defined UIs.
• Nice UI builder.
• Potentially tons of GNOME stuff to leverage.
• Code seems grainy but otherwise understandable.
• Easy to install if using distro packages.

Neutral/undecided

• Event handling is simple event→callback; no “listener” or signal/slot concepts.
• Event names are specified as strings.

Cons

• Poor support on other operating systems.
• GTK3 is the future and it is built for GNOME. For other desktop environments, who knows how well it will work and what will be supported. Will a ton of GNOME dependencies eventually be required?

Thoughts

• Workflow (UI layout to code) is pleasant.
• Perhaps best option for Linux-centric apps—unless/until some GNOME heaviness/goofiness happens.

Pros

• First class Linux framework.
• Excellent multiplatform support (except maybe non-GNOME GTK).
• Lots of components (including “we do it differently” DBUS, etc.)
• Used by Spyder and a lot of others.

Cons:

• GPL-only or commercial license is at ~$500. (PySide is LGPL, but there has been little development.)
• Qt code can be heavy, somewhat verbose.
• Possibly PITA to install if not using distro repos (which you want because it moves so fast).¹⁾

Thoughts

• Perhaps best option for multi-platform FOSS apps and for proprietary apps that have a $500 tools budget.

Pros

• Liberal license.
• True multi-platform support (e.g., native icons, native order dialog buttons).
• ? install (suspect easy if distro repos are used)

Cons

• Second-class Linux framework.
• Awkward external UI builder (wxGlade is incomplete, wxFormBuilder requires building, wxSmith is integrated with Code::Blocks)
• wxFormBuilder generates .fbp files which are XML—but not really human readable.
• Tiny bit awkward external UI file export/import mechanism (no UI file format, export a class with GUI, in program subclass it to make your wired-up window.).
• Code seems awkward at times (perhaps it's only oddly named components)

Awkward points:

• In wxville, a Frame is a window, a Window is the mega-parent class, a Control is a widget.
• Method names are CamelCase (first capitalized).
• Events: self.Bind(event-type, handler, emitting-object)

Thoughts

• Perhaps best option for multi-platform proprietary apps that have zero budget.

Interesting, but not really a desktop application framework. Good for touch interfaces.

Pros

• MIT license.

Needs research

Pros

• LGPL

Is a wrapper around desktop toolkits. On Linux, wraps PyGTK right now, PyGObject in the future.