I undusted recently my old G5 and tried to use 12.11 via Macports, it compiled and installed pretty flawlessly, but same issue as I had long ago, if not started within an .app there is no focus on the app, I couldn't click anything. Unfortunately I couldn't use it, because it wouldn't start up, usually hung with 100% CPU usage, already when only using compiler plugin. I found a possible fix here in the forums for the codecompletion plugin (
http://forums.codeblocks.org/index.php?topic=17238.0 ), but I didn't come that far... I also once had a working version of 12.11 (some pre) on an older hdd which crashed, so no idea what this hung already in libcompilerplugin is caused by, unfortunately gdb gave me not much to work with.
Then I noticed release of 13.12 and gave it a try.
This all may or may not depending on old 10.5, but using Macports I am able to use any gcc up to 4.8 without any trouble.
I had to do several modifications in order to make it compile in configure:
-force_load flag was set although the compiler didn't support it (none, up to gcc4.8 )
--no-undefined flag didn't work
-Wno-unused-local-typedefs didn't work on 4.8
When using gcc4.7 or 4.8 the compilation broke due to unresolved dependencies to restGPRx and 2 others like that, unfortunately didn't write them down, sorry. So in the end I used gcc4.3 for the moment.
Then in CallTip.h I had to add #include <string> to make it compile, it broke with some missing type definition for std::string otherwise:
./src/scintilla/src/CallTip.h:20: error: field 'val' has incomplete type
./src/scintilla/src/RESearch.h:46: error: field 'pat' has incomplete type
The old bug with starting from an console and no focus is partially gone, can scroll and click "x" to close the window, but can't confirm (yes/no) the question about layout (perspective) change then. Not vital anymore at least since I learned that I can start it without a problem in an .app.
Major problem is, it won't recognize any plugin now. No matter where I put them, I always get:
Scanning for plugins in /Users/smir/Library/Application Support/codeblocks/share/codeblocks/plugins
Loaded 0 plugins
Scanning for plugins in /Applications/CodeBlocks.app/Contents/Resources/share/codeblocks
Loaded 0 plugins
Not sure yet if it depends on -force_load but for any suggestions how to get more information about how to debug this I am more than grateful.
Other than that I hope that some of my information here may help others.

Update:
-force_load flag seems to be an issue of underlying XCode < 3.2 from what I found.
I rebuilt 13.12 now on 10.5.8 intel, same problem that no plugins can be found, so it is no PPC specific problem at least.
The prebuilt binary crashes instantly, so I can't compare, but from the content I noticed that it has .dylib files instead of the .so files I get in my compilation (although this didnt seem to cause problems in 12.11)
Update2:
alright, the extension is the problem. Symlinking the .so to .dylib makes it find and use the plugins. So only question is now, if this is intended behavior that it only digs for dylib and if so why it creates .so instead.
Update3:
It works now flawlessly (including codecompletion plugin) on intel version, but 13.12 still freezes with 100% CPU usage on PPC like 12.11 did. So this problem is the one to debug now.
Here it gets stuck it seems, trying to track down now:
#0 0x94245c4c in GetCGSConnectionID ()
#1 0x93e12478 in FlushWindowObject ()
#2 0x93e11fdc in FlushAllBuffers ()
#3 0x914f3da4 in __CFRunLoopDoObservers ()
#4 0x914f4e18 in CFRunLoopRunSpecific ()
#5 0x93e10b18 in RunCurrentEventLoopInMode ()
#6 0x93e1093c in ReceiveNextEventCommon ()
#7 0x016f2a70 in wxApp::Yield ()
#8 0x01abb05c in wxYield ()
#9 0x016e8288 in wxGUIAppTraits::WaitForChild ()
#10 0x01abd854 in wxExecute ()
#11 0x01abdc60 in wxExecute ()
#12 0x01abb604 in wxDoExecuteWithCapture ()
#13 0x00b7e100 in Compiler::EvalXMLCondition (this=0x2099800, node=0x62165c0) at compiler.cpp:1209
#14 0x00b85ee0 in Compiler::LoadDefaultOptions (this=0x2099800, name=@0x20999dc, recursion=0) at compiler.cpp:828
#15 0x00b88b54 in Compiler::Reset (this=0x2099800) at compiler.cpp:161
#16 0x06444094 in CompilerMINGW::CompilerMINGW (this=0x2099800, name=@0xbfffed54, ID=@0xbfffed50) at compilerMINGW.cpp:35
#17 0x0641d118 in CompilerGCC::DoRegisterCompilers (this=0x632d2c0) at compilergcc.cpp:851
#18 0x064336d4 in CompilerGCC::OnAttach (this=0x632d2c0) at compilergcc.cpp:360
#19 0x00b40ddc in cbPlugin::Attach (this=0x632d2c0) at cbplugin.cpp:71
#20 0x00c58898 in PluginManager::AttachPlugin (this=0x6311460, plugin=0x632d2c0, ignoreSafeMode=false) at pluginmanager.cpp:195
#21 0x00c5bd0c in PluginManager::LoadAllPlugins (this=0x6311460) at pluginmanager.cpp:1117
#22 0x00085c84 in MainFrame::ScanForPlugins (this=0x2082600) at main.cpp:1157
#23 0x000a2bf0 in MainFrame::MainFrame (this=0x2082600, parent=0x0) at main.cpp:608
#24 0x0000d6f8 in CodeBlocksApp::InitFrame (this=0x1e3dba0) at app.cpp:437
#25 0x00010454 in CodeBlocksApp::OnInit (this=0x1e3dba0) at app.cpp:661
#26 0x000123d4 in wxAppConsole::CallOnInit (this=0x1e3dba0) at app.h:76
#27 0x01a64fe4 in wxEntry ()
#28 0x0000ac98 in main (argc=1, argv=0xbffff9b8) at app.cpp:276
Update, I thought to give it a try, but when I compile against wxWidgets 3.0 I get the following error during startup:
wxWidgets Debug Alert
../src/osx/carbon/region.cpp(1016): assert "m_refData" failed in DoOffset(): invalid wxRegion
Call stack:
[00] wxWidgetCocoaImpl::drawRect(void*, NSView*, void*)
[01] wxOSX_drawRect(NSView*, objc_selector*, _NSRect)
[02] -[NSView _drawRect:clip:]
[03] -[NSView _recursiveDisplayAllDirtyWithLockFocus:visRect:]
[04] -[NSView _recursiveDisplayAllDirtyWithLockFocus:visRect:]
[05] -[NSView _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:]
[06] -[NSNextStepFrame _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:]
[07] -[NSView _displayRectIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:]
[08] -[NSWindow displayIfNeeded]
[09] -[NSWindow _reallyDoOrderWindow:relativeTo:findKey:forCounter:force:isModal:]
[10] -[NSWindow makeKeyAndOrderFront:]
[11] wxNonOwnedWindowCocoaImpl::Show(bool)
[12] wxNonOwnedWindow::Show(bool)
[13] cbSplashScreen::cbSplashScreen(wxBitmap&, long, wxWindow*, int, long)
[14] (anonymous namespace)::Splash::Splash(bool) app.cpp:25
[15] CodeBlocksApp::OnInit() app.cpp:65
[16] wxApp::CallOnInit()
[17] wxEntry(int&, wchar_t**)
[18] main app.cpp:27
[19] start
Unfortunately this is "fatal" again for me, since I can't click any of the buttons ^^
Update 5:
disabled splash screen for now, with the result that it starts up now finally, finds the compiler and then leaves me alone with an empty, grey window, doing nothing...
Also tried with latest SVN, same result.