DeskTop: Fix type-down and tab selection if active window empty

Follow-up to ea36d00 which violated the implicit assumption that the set of "selectable icons" was non-empty. It can be, so explicitly check and early-exit.
a2stuff · Oct 9, 2024 · a0b44c5 · a0b44c5
1 parent ea36d00
commit a0b44c5
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Showing 2 changed files with 12 additions and 3 deletions.
diff --git a/desktop/main.s b/desktop/main.s
@@ -3403,7 +3403,12 @@ next:   lda     #$00
 
 ;;; Figure out current selected index, based on selection.
 
-common: lda     selected_icon_count
+common:
+        ;; Anything selectable?
+        lda     buffer
+        RTS_IF_EQ
+
+        lda     selected_icon_count
         beq     pick_first
 
         ;; Try to find actual selection in our list
@@ -3506,9 +3511,10 @@ file_char:
 
         ;; Collect and sort the potential type-down matches
         jsr     GetNameSelectableIconsSorted
+        lda     num_filenames
+        beq     done
 
-        ;; Find a match. There will always be one, since
-        ;; desktop icons (including Trash) are considered.
+        ;; Find a match.
         jsr     FindMatch
 
         ;; Icon to select

diff --git a/res/notes/testplan.md b/res/notes/testplan.md
@@ -248,6 +248,9 @@
     * Clear selection. Press Shift+Tab repeatedly. Verify that icons in the active window (or desktop if no window is open) are selected in reverse lexicographic order.
     * Select an icon. Press Shift+Tab. Verify that the previous icon in the active window (or desktop if no window is open) in lexicographic order is selected.
 
+* Open a volume window containing no file icons. Clear selection by clicking on the desktop. Press Tab repeatedly. Verify selection does not change, scrollbars do not appear in the window, and DeskTop does not crash. Close the window. Verify that the volume icon is no longer dimmed.
+* Open a volume window containing no file icons. Clear selection by clicking on the desktop. Type 'Z' repeatedly. Verify selection does not change, scrollbars do not appear in the window, and DeskTop does not crash. Close the window. Verify that the volume icon is no longer dimmed.
+
 
 * Launch DeskTop. Open a volume containing no files. Verify that the default minimum window size is used - about 170px by 50px not counting title/scrollbars.