NsCDE is not a mere clone of CDE. Under the first visual impression, there are unintentional and intentional differences.
First of all, it is not a standalone Window Manager or Desktop Environment written in some language(s). It is a patchwork which owns 80% of it's functionality to wonderful and powerful Window Manager of FVWM. Other parts are configurations, scripts and programs which are making the whole thing to function like the combination of the CDE experience and modern powerful X Window Manager. Here are some things that I can recall to be different - for the worse or for the better, user's opinion may vary.
What is similar or the same:
There is a recognizable titlebar and buttons
Titlebar buttons have the same basic (left click) actions as CDE
Color themes and theming
Front Panel and subpanels
Workspace Manager
Workspace Menu / Root Menu (right click on the root window)
Workspaces (desks)
Most of the icons reused
Backdrops
Style Manager launcher and most of the Style Managers
Occupy Workspace/Page dialog
Workstation Info window (as found in Solaris CDE)
FpLite (not with the same function)
Front Panel clock, calendar and check mail
Icon positioning
Look and feel via FVWM Styles
Nice vintage but somewhat irritating wait cursor in the sand clock shape
Various misc small imitations ...
Differencies exist: for worse or better. They are described here in detail with complete explanations:
Workspace Manager has a four default choices for workspaces (desks). As in CDE four is a
default, but combinations with 2, 6 and 8 are possible. Workspace Manger can be of dynamic
width when number of workspaces is changed, or it can be of fixed width if InfoStore
variable wsm.eco is set to 1 in $FVWM_USERDIR/NsCDE.conf
.
No drag and drop. This is specially visible in Install Icon action which actually calls custom tool Subpanel Manager for this actions. Subpanel Manager itself will be rewritten in a nicer and less buggy way on the first good occasion.
No Dt Actions builder, and never will be. Write FvwmScript scripts or use some toolkit in combination with python, perl ...
No Application Manager. If integration with Install Icon and possibly menus will be possible with some file manager, it may be (re)invented in the future.
Keybindings are 90% custom made, and user have a choice to use it or - partially or totally rewrite it. There are more functions and actions in NsCDE than in CDE, and hence there are a lot of key bindings.
Mouse bindings - some actions like Workspace Menu in CDE are mimicked in NsCDE, titlebar and titlebar buttons too, but since there is no much of them in original CDE anyway, there is a plenty of custom mouse bindings and mouse bindings in combination with modifier keys. As for keybindings apply: use it or write your own.
Color Style Manager has numerous new functions: Gtk and Qt integration, X resources integration is optional, and it has even a possibility to run a custom script with required parameters of current palette and number of colors for external and marginal color scheme integrations - like Gkrellm for example. Palette color editor is missing. It should be possible to write it in the FvwmScript in some future version update.
Font Style Manager is totally NsCDE oriented and doesn't work much as font management in CDE. NsCDE supports XFT fonts (disable antialiasing if you want extreme original look) and it combines 5 groups of fonts in 3 sizes described in this documentation.
Keyboard Style Manager implements all options supported by the xset(1) on PC. CDE original in default installation at least, seems to have only auto-repeat and click volume controls.
Mouse Style Manager does not have configurable middle mouse (button 2) action since this is not applicable very much on today's GUI widgets.
Beep Style Manager has a additional Beep button for testing during setup.
Screensaver Style Manager is in fact Xscreensaver setup. Perfect drop in replacement and much fancier than original.
Window Style Manager manages much more of window, icon, pages and animation behavior than original program in CDE, and even this is a small subset of options in FVWM. See it's documentation and fvwm(1) man page.
Power Style Manager is actually very rare in Style Manager across old CDE setups. It manages DPMS setting of the monitor with xset(1).
Startup Style Manager is available only if NsCDE is started under some X Session Manager. It detects supported DE's and starts appropriate settings tool for that desktop environment if it is found.
Pages: not present in CDE in best of my knowledge. Only workspaces (desks) in original. Page Manager (PGM) is a custom FrontPanel icon which is using place left bottom of the Workspace Manager. It popups menu with the list of pages and can change current page.
Custom keyboard and mouse actions on titlebars, buttons and root window.
WsPgMgr - Manage Workspaces and Pages. NsCDE invention.
GeometryMgr - Manages custom X11 window starting size and position.
FpLite is measuring system load, not desktop activity. It has much more fine grained indication of activity with colors, and it's height is 3x of the original for a better visibility. On click it is calling FVWM function which will run terminal program with top or similar program, or anything else if use overrides that function in local configuration.
Calendar and Mail widgets are placeholders and simple indicators which are expected to be extended with already named functions to do what user wants.
Probably some more small differences.