ubuntu-ui-toolkit-examples is uninstallable in that environment indeed: It depends on qtdeclarative5-ubuntu-ui-toolkit-plugin (= 0.1.49+14.10.20140715-0ubuntu1), i. e. a versioned dependency. This won't be satisfied by the "Provides: qtdeclarative5-ubuntu-ui-toolkit-plugin" of qtdeclarative5-ubuntu-ui-toolkit-plugin-gles, but this is installed by default.
So ubuntu-ui-toolkit-examples either needs to drop the strict versioned dependency (so that the Provides: gets effective), or grow an alternative dependency to qtdeclarative5-ubuntu-ui-toolkit-plugin-gles.
ubuntu- ui-toolkit- examples is uninstallable in that environment indeed: It depends on qtdeclarative5- ubuntu- ui-toolkit- plugin (= 0.1.49+ 14.10.20140715- 0ubuntu1) , i. e. a versioned dependency. This won't be satisfied by the "Provides: qtdeclarative5- ubuntu- ui-toolkit- plugin" of qtdeclarative5- ubuntu- ui-toolkit- plugin- gles, but this is installed by default.
So ubuntu- ui-toolkit- examples either needs to drop the strict versioned dependency (so that the Provides: gets effective), or grow an alternative dependency to qtdeclarative5- ubuntu- ui-toolkit- plugin- gles.