Dialogs: Don't need to FindWindow when testing for I-beam cursor

On mouse move, dialogs with LineEdit controls need to test if the
cursor is over the control and update the cursor shape appropriately.
The File Dialog and DeskTop's Rename (etc) dialog first did a
FindWindow to see if the cursor was over the window - that's not
necessary since the dialog is modal! Just delete the code, everything
is faster and smaller (-27 bytes each).

No functional changes.

desktop/main.s

@@ -13404,16 +13404,7 @@ appleworks:
         jsr     CheckMouseMoved
         bcc     PromptInputLoop
 
-        MGTK_CALL MGTK::FindWindow, findwindow_params
-        lda     findwindow_params::which_area
-        beq     PromptInputLoop
-
-        lda     findwindow_params::window_id
-        cmp     #winfo_prompt_dialog::kWindowId
-        bne     PromptInputLoop
-
-        ;; Is over this window... but where?
-        copy    winfo_prompt_dialog, event_params
+        copy    winfo_prompt_dialog, screentowindow_params::window_id
         MGTK_CALL MGTK::ScreenToWindow, screentowindow_params
         MGTK_CALL MGTK::MoveTo, screentowindow_params::window
         MGTK_CALL MGTK::InRect, name_input_rect

lib/file_dialog.s

@@ -174,17 +174,6 @@ key_handler_hook:
         copy    #0, type_down_buf
 
 .ifdef FD_EXTENDED
-        MGTK_CALL MGTK::FindWindow, findwindow_params
-        lda     findwindow_params::which_area
-        jeq     EventLoop
-
-        lda     findwindow_params::window_id
-        cmp     #file_dialog_res::kFilePickerDlgWindowID
-        beq     l1
-        jsr     _UnsetCursorIBeam
-        jmp     EventLoop
-
-l1:
         jsr     _MoveToWindowCoords
 
         bit     extra_controls_flag