Here's
DrOpen, an AHK script I think does what you ask!
To run, save as DrOpen.ahk and install
AutoHotkey.
;DrOpen.ahk
; Drop files on a window to open the files in an associated program.
; Syntax: DrOpen "<command>"
; Example: DrOpen "c:\windows\notepad.exe"
;Skrommel @2007
xpos:=100
ypos:=0
width:=100
height:=0
#NoEnv
#SingleInstance,Off
SplitPath,1,name,dir,ext,name_no_ext,drive
Gui,+ToolWindow +AlwaysOnTop
Gui,Show,x%xpos% y%ypos% w%width% h%height%,%name_no_ext%
Return
GuiDropFiles:
ToolTip,%A_GuiControl%
Loop, parse, A_GuiControlEvent, `n
Run,%1% %A_LoopField%
Return
GuiClose:
ExitApp