The mouse pointer only moves up and down or left and right, not both.
The M0100 mouse is known to have compatibility issues with the Apple IIc and IIc Plus where the mouse may not be detected, or one axis may stop being measured. This is due to a hardware problem affecting only some mice with that model number. Mice with model numbers starting with A2 should function correctly. This problem is not specific to Apple II DeskTop. More details and a fix.
Double-clicking on icons doesn't open them.
On systems with an accelerator running at more than 1MHz, or emulators, a double-click might not be detected. Go to Apple > Control Panels and open Control.Panel (using File > Open or △-O) then click a different Double-Click Speed option.
On systems without an accelerator and running at just 1MHz, you may be clicking too fast for the computer to notice you've clicked twice. Try clicking more slowly.
My system has a clock but I don't see the time on the menu bar.
ProDOS needs a driver to talk to the clock. If you're booting your machine using a DeskTop disk image then no driver is present. Instead, boot ProDOS off a disk with your clock driver, then start DeskTop by launching DESKTOP.SYSTEM. A generic clock driver named CLOCK.SYSTEM is included on DeskTop live installation disk images.
The screen has color fringes everywhere and text is difficult to read.
Apple II DeskTop uses monochrome double hi-res graphics. On systems with a color composite monitor, the monochrome dot patterns are interpreted as color. While this was true on vintage color displays, the problem is worse with modern composite-to-VGA adapters or modern LCD displays.
On the following systems, the video mode will switch automatically from color to monochrome:
The Apple IIgs with a composite or analog RGB monitor.
The Apple IIc with a Video 7 RGB Interface adapter, and with a digital RGB monitor.
In MAME, enter the menu (press the Delete key or Fn+Delete, then press the Tab key), select Machine Configuration, and for Monitor type select Video-7 RGB.
In AppleWin, for Video settings select Color (RGB Card/Monitor).
In Apple //jse, under Options, ensure both Mono Screen and GL Renderer are disabled.
Otherwise, you will need to switch modes manually if you can:
The AppleColor Composite Monitor has a color/monochrome toggle button in the control panel.
The Laser 128 line of computers have a MONO/COLOR switch above the keyboard.
The Apple IIe Option Card for Macintosh has Monochrome and Color display options in the IIe Option Panel.
The Virtual ][ emulator has a color/monochrome toggle button on the toolbar.
The a2heaven.com Apple IIc VGA Adapter has a button to toggle modes.
You can modify an Apple IIc to add a monochrome/color switch. See YouTube video by Scott Lawrence.
Otherwise, you will need to use an actual monochrome monitor to see Apple II DeskTop as intended.
I don't see any desk accessories in the Apple menu.
There is not enough room on 140k floppy disks to include desk accessory files. The 140k floppy disk images are really intended for installing Apple II DeskTop onto a hard disk, not for running DeskTop.
I have a ZIP CHIP but the System Speed DA buttons don't change the speed.
This can happen if you have your mouse card in a slot that causes the ZIP CHIP to run at "normal" speed instead of "fast" speed. Use the ZIP.SYSTEM utility to set your mouse card slot to "fast", or move your mouse card to a default "fast" slot (1 or 4).
File and volume names are capitalized strangely.
ProDOS-8 doesn't support lowercase filenames directly. Files and volumes named using the Apple IIgs Finder as well as AppleWorks files will appear with the specified mix of uppercase and lowercase letters, which may be all uppercase if named while Caps Lock was down. Other files and volumes will have uppercase and lowercase letters inferred using an algorithm.
When using arrow keys to navigate menus, it skips over items.
In the MAME emulator, by default the arrow keys move the mouse as well, and this double movement confuses DeskTop. In MAME, enter the menu (press the Delete key or Fn+Delete, then press the Tab key), select Input Settings, then Input Assignments (this system) then highlight Mouse X Analog Inc and press fn+delete. Repeat this for Mouse X Analog Dec, Mouse Y Analog Inc, and Mouse Y Analog Dec. Then press Escape to exit and save the settings.
DeskTop doesn't start with my experimental version of ProDOS.
DeskTop assumes full compatibility with the documented ProDOS-8 MLI and global page. It works with official ProDOS versions from 1.1 to 2.0.3 and unofficial ProDOS version 2.4. Several experimental versions of ProDOS make breaking changes to this API which are not compatible with DeskTop. ProDOS 2.5 changes unit number encoding and time encoding. ProDOS.FX changes flag results from MLI calls and enforces case-sensitive filename usage.