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Please notice that the multi-level menus (eg Inbox > Actions > Mark) have the tendency to disappear when moving the cursor diagonally to the item on the second level (for example Spam). That is because the menu entry below Actions, that is Delete, either has no menu or it has a different menu. The only way to access a second level menu is to move the cursor horizontally along the menu, then vertically within the second menu.
The fix to this is to have a small delay before switching menu entries.This applies to all multi-level menus in SmarterTools and SmarterTrack. It is not critical, but it surely is annoying.