I was running into the same issue too. It turns out that on some machines Shift-F5 is mapped to Shift-XF86_Switch_VT_5. My patch includes a workaround. The same workaround was used for Shift-F4.
Andrew Wong (1):
gitk: Add workaround for system where Shift-F5 mapped to
Shift-XF86_Switch_VT_5gitk-git/gitk | 1 + 1 file changed, 1 insertion(+)
-- 1.7.12.1.382.gb0576a6