Currently gdesklets install image files under /usr/lib/gdesklets. As they are platform independent, they should be put under /usr/share/gdesklets instead.
Here's the relevant log generated by lintian when packaging gdesklets Debian package:
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Additions/bg/fancy-blue.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Additions/bg/grass.png
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W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Additions/bg/old-paper2.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Globe/1.png
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W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Globe/12.png
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W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Globe/bg.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Globe/free.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Globe/restart.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Gnome/1.png
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W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Gnome/2.png
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W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Gnome/4.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Gnome/5.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Gnome/6.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Gnome/7.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Gnome/8.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Gnome/9.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Gnome/bg.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Gnome/free.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Gnome/restart.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Numbers/1.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Numbers/10.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Numbers/11.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Numbers/12.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Numbers/13.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Numbers/14.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Numbers/15.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Numbers/2.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Numbers/3.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Numbers/4.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Numbers/5.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Numbers/6.png
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W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Numbers/bg.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Numbers/free.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Numbers/restart.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Tux/1.png
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W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Tux/12.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Tux/13.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Tux/14.png
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W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Tux/6.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Tux/7.png
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W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Tux/bg.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Tux/free.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/Tux/restart.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/gDesklets/1.png
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W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/gDesklets/11.png
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W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/gDesklets/9.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/gDesklets/bg.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/gDesklets/free.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/15pieces/gDesklets/restart.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Calendar/cal.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Calendar/months/0.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Calendar/months/1.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Calendar/months/10.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Calendar/months/11.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Calendar/months/12.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Calendar/months/2.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Calendar/months/3.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Calendar/months/4.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Calendar/months/5.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Calendar/months/6.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Calendar/months/7.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Calendar/months/8.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Calendar/months/9.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Clock/gfx/aero.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Clock/gfx/chrome.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Clock/gfx/default.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Clock/gfx/dull.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Clock/gfx/fx.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Clock/gfx/fxtux.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Clock/gfx/gd.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Clock/gfx/gnome.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Clock/gfx/modern.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Clock/gfx/moon.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Clock/gfx/osX.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Clock/gfx/pocketwatch.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Clock/gfx/raf.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Clock/gfx/rome.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Clock/gfx/station.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Clock/gfx/tux.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/Displays/Quote-of-the-Day/quote.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/data/about.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/data/calendar.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/doc/basic/Images/desklet-context-menu.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/doc/basic/Images/desklet-start-shell.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/doc/basic/Images/gdesklets.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/doc/basic/Images/open-command.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/doc/basic/Images/preferences.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/doc/basic/Images/profile.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/doc/basic/Images/remote.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/doc/basic/Images/shell.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/shell/plugins/ControlBrowser/author.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/shell/plugins/ControlBrowser/control.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/shell/plugins/ControlBrowser/folder.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/shell/plugins/ControlBrowser/interface.png
W: gdesklets: image-file-in-usr-lib usr/lib/gdesklets/shell/plugins/DisplayBrowser/author.png
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Deferred to 0.36.2