Support in other apps:
- In apps and dialogs of the Windows OS, you can generally use either F4, Alt+Down, or Alt+Up to open a drop-down control.
- In Windows open/save dialogs, however, you must use Alt+Down to be able to open any kind of drop-down control. F4 specifically opens the location bar drop-down from anywhere in the dialog. And Alt+Up visits the parent directory.
- In the GDK-based calculator app Qalculate (in the settings dialog), Alt+Down is the only one that works, F4 and Alt+Up don't.
- In the Qt-based MKVToolNix, only Alt+Down and F4 work, Alt+Up doesn't.
Problems in DOpus:
- F4 mostly works to open some drop-down or menu. In the rename dialog, e.g., it doesn't work - neither for classic drop-down controls nor for dialog-toolbar-like drop-down buttons, whereas F4 works for the latter in the customization dialog.
- Support for Alt+Down is worse. In a lister's search and filter controls, or with drop-down buttons (in dialog toolbars or tiny dialogs with message, buttons, and maybe a text box), e.g., it doesn't work. (I think when Alt+Down works, Alt+Up works also.)
- With some drop-down controls like the search or the filter control, you get two kinds of drop-down list when using the mouse, but only one of them is accessible via keyboard using F4 - whether it's the left or right one differs.
- Some text boxes in the preferences dialog with a stack icon on the left that and no arrow on the right, there's no way to show the stack icon's menu using the keyboard.
Possible improvements:
- When there's just one drop-down, F4 as well as Alt+Down (and Alt+Up) should show it.
- This should also work for button-like dialog toolbars like in the customization or rename dialogs.
- When there are two drop-down lists, you could go by the open/save dialog's behavior where Alt+Down is more specific and F4 is more general in the sense that the location bar doesn't have to be focused to open it using F4. This would mean showing the drop-down list associated with the arrow on the right side when pressing Alt+Down (or Alt+Up), and showing the special drop-down list associated with the icon on the left side when pressing F4.
- In the preferences dialog where Alt+Down and Alt+Up are bound to changing pages, you'd have to compromise and probably favor showing the drop-down list. This would mean one has to change control focus to change the page using Alt+Down/Alt+Up.
- In text boxes with an icon on the left side, F4 should work to show the icon menu. You could decide to make Alt+Down (or Alt+Up) work also for the same thing, but this may also be viewed as inconsistent.