Comment 4 for bug 308605

Tested some cases.

> BAT files to start Firefox. -no-remote can be replaced by "SET MOZ_NO_REOTE=1".
> Multiple profiles exist when tested.
> (A) Start in Remote_Mode
> (A-1) Remote_Mode_Existent_Prof : firefox.exe -P "Existent_Prof"
> (A-2) Remote_Mode_Non_Existent_Prof : firefox.exe -P "Non_Existent_Prof"
> (A-3) Remote_Mode_No_Prof : firefox.exe -P
> (B) Start in No_Remote_Mode
> (B-1) No_Remote_Mode_Existent_Prof : firefox.exe -no-remote -P "Existent_Prof"
> (B-2) No_Remote_Mode_Non_Existent_Prof : firefox.exe -no-remote -P "Non_Existent_Prof"
> (B-3) No_Remote_Mode_No_Prof : firefox.exe -no-remote -P

(Case-1) First kick of Firefox
  In any first kick of Firefox,
     (A-1)/(B-1) : Fx starts using specified profile
     (A-2)/(A-3)/(B-2)/(B-3) : Profile selection dialog is displayed

(Case-2) Start second Firefox

(Case-2-1) Already started Firefox : (A-1) Remote_Mode_Existent_Prof
(Case-2-1-1) Second Fx : (B-1) No_Remote_Mode_Existent_Prof
             => Firefox is already running, but is not responding
(Case-2-1-2) Second Fx : (B-2) No_Remote_Mode_Non_Existent_Prof
             => Firefox is already running, but is not responding
(Case-2-1-3) Second Fx : (B-3) No_Remote_Mode_No_Prof
             => Profile selection dialog is displayed

(Case-2-2) Already started Firefox : (B-1) No_Remote_Mode_Existent_Prof
(Case-2-2-1) Second Fx : (A-1) Remote_Mode_Existent_Prof
             => Firefox is already running, but is not responding
(Case-2-2-2) Second Fx : (A-2) Remote_Mode_Non_Existent_Prof
             => Profile selection dialog is displayed
(Case-2-2-3) Second Fx : (A-3) No_Remote_Mode_No_Prof
             => Profile selection dialog is displayed
(Case-2-2-4) Second Fx : (B-1) Remote_Mode_Existent_Prof
             => Firefox is already running, but is not responding
(Case-2-2-5) Second Fx : (B-2) Remote_Mode_Non_Existent_Prof
             => Firefox is already running, but is not responding
(Case-2-2-6) Second Fx : (B-3) No_Remote_Mode_No_Prof
             => Profile selection dialog is displayed

When profile selection dialog is displayed, and if already used profile is chosen, warning of "profile is in use" is issued.
Warning of "..., but is not responding" looks for me to be wrong(then misleading) warning problem when parent.lock exists or specified profile is not found.
In any case of "profile is in use" or "profile not found", I think profile selection dialog is kind for user if multiple profiles exist, but I think proper warning is sufficient.