DeskTop: Prompt to re-insert system disk for Apple Menu items

This worked in A2D 1.1 but regressed in 1.2 when support for placing
arbitrary files in the Apple Menu was added. Add an entry point that
sets a flag to prompt/retry, and use it from the Apple Menu "DA" item
invocation.

(Also, do a spellcheck pass on the test plan.)

RELEASE-NOTES.md

@@ -30,6 +30,7 @@ Project Page: https://github.com/a2stuff/a2d
 * Special > Make Alias now creates link file in same directory as original.
 * Add Edit menu with Cut/Copy/Paste/Clear, relocate Select All.
 * Ensure the modification date for copied folders matches the original.
+* Prompt to re-insert system disk when launching Apple Menu items.
 
 ### Selector
 

desktop/main.s

@@ -877,6 +877,12 @@ tmp_path_buf:
 ;;; Inputs: Path in `src_path_buf` (a.k.a. `INVOKER_PREFIX`)
 
 .proc LaunchFileWithPath
+        clc
+        bcc     :+              ; always
+sys_disk:
+        sec
+:       ror     sys_prompt_flag
+
         jsr     SetCursorWatch ; before invoking
 
         ;; Assume no interpreter to start
@@ -886,9 +892,18 @@ tmp_path_buf:
         param_call MakePathAbsolute, src_path_buf
 
         ;; Get the file info to determine type.
-        jsr     GetSrcFileInfo
+retry:  jsr     GetSrcFileInfo
         bcc     :+
-        jmp     ShowAlert
+
+        sys_prompt_flag := *+1
+        lda     #SELF_MODIFIED_BYTE
+        jpl     ShowAlert
+
+        lda     #kErrInsertSystemDisk
+        jsr     ShowAlert
+        cmp     #kAlertResultOK
+        beq     retry           ; ok, so try again
+        rts                     ; cancel, so fail
 
         ;; Check file type.
 :       copy    src_file_info_params::file_type, icontype_filetype
@@ -1164,6 +1179,7 @@ check_header:
         DEFINE_GET_PREFIX_PARAMS get_prefix_params, INVOKER_INTERPRETER
 
 .endproc ; LaunchFileWithPath
+LaunchFileWithPathOnSystemDisk := LaunchFileWithPath::sys_disk
 
 ;;; ============================================================
 
@@ -1670,7 +1686,7 @@ skip:   iny
         stx     path
 
         ;; Allow arbitrary types in menu (e.g. folders)
-        jmp     LaunchFileWithPath
+        jmp     LaunchFileWithPathOnSystemDisk
 .endproc ; CmdDeskaccImpl
 CmdDeskAcc      := CmdDeskaccImpl::start