I like the idea, and the support for a relatively new digital book format, so good for you Carsten to program/realise something to handle these book files.
The only problem, and I appreciate it's only an early alpha release at this stage, is that the books I downloaded from the Free download sites, e.g.
epubBooks.com -The Woman in White by Wilkie Collins don't allow the books to be read, only a few words on sporadic pages are viewable at this stage, but as it's a work in progress I hold off on any crticism, and I am just mentioning this situation as an observation, and hope that further work on the program will bear fruit, for you, and then for all MorphOS users.
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MacMini 1.5GHz,64MB VRAM, PowerBooks A1138/9 (Model 5,8/9),PowerMac G5 2.3GHz(DP), iMac A1145 2.1GHz 20", all with MorphOS v3.18+,Airport,Bluetooth,A1016 Keyboard,T-RB22 Mouse,DVD-RW-DL,MiniMax,Firewire/USB2 & MacOSX 10.4/5