Description of problem:
I click the button "uninstall" to remove pitivi

Version-Release number of selected component:
gnome-software-3.9.3-1.fc20

Additional info:
reporter:       libreport-2.1.7
backtrace_rating: 4
cmdline:        gnome-software
crash_function: _gtk_css_value_compute
executable:     /usr/bin/gnome-software
kernel:         3.11.1-300.fc20.x86_64
runlevel:       N 5
type:           CCpp
uid:            1000

Truncated backtrace:
Thread no. 1 (10 frames)
 #0 _gtk_css_value_compute at gtkcssvalue.c:100
 #1 gtk_css_value_initial_compute at gtkcssinitialvalue.c:81
 #2 _gtk_css_value_compute at gtkcssvalue.c:107
 #3 _gtk_css_computed_values_compute_value at gtkcsscomputedvalues.c:146
 #4 _gtk_css_lookup_resolve at gtkcsslookup.c:166
 #5 build_properties at gtkstylecontext.c:995
 #6 style_data_lookup at gtkstylecontext.c:1035
 #7 _gtk_style_context_validate at gtkstylecontext.c:3288
 #20 gtk_container_idle_sizer at gtkcontainer.c:1680
 #21 _g_closure_invoke_va at gclosure.c:840