Cursor themes from xcursor-themes (wonderland etc, http://xorg.freedesktop.org/releases/individual/data/ ) are not fully supported by Plasma 5 KWin. For example, mouse cursor doesn't change when trying to resize windows. It's a regression compared to KDE Workspace 4. Reproducible: Always
There's "QString XCursorTheme::findAlternative(const QString &name) const" function in plasma-desktop/kcms/input/xcursor/xcursortheme.cpp , it handles xcursor names to match Qt/KDE cursor names. Maybe KWin needs something like that too.
Very much likely dupe, thus fixed in 5.3 - you may either check whether the shape resolution in http://commits.kde.org/kwin/e2c422dcb54317acc42ca252d449f096ad78d7ea matches your needs or list the contents of your theme. Also see http://kde-look.org/content/show.php/Cursor+theme+"fixing"+script?content=161037 *** This bug has been marked as a duplicate of bug 344006 ***
Indeed, seems to be fixed in master already.
The fix is: http://quickgit.kde.org/?p=kwin.git&a=commitdiff&h=3aa4c8d635e25117075121bb40040f9be6ac2c44
*** This bug has been marked as a duplicate of bug 344006 ***
Well, not really a duplicate of #344006. This issue is about missing alternatives, not about broken cursor.