XOR support for mouse cursors

Ben Swartzlander ben at swartzlander.org
Sat Nov 10 14:45:44 PST 2007

Didn't Microsoft Windows 3.0 have XOR cursors? How is it possible to 
patent something that already existed in a shipping product at the time? 
SDL currently has XOR cursors -- why haven't they been sued?

Just so I understand, is it the case that the X.org team has considered 
implementing XOR cursors, and opted not to purely out of legal fears? Or 
has it never seriously been considered?

-Ben Swartzlander

Russell Sears wrote:
> There's also a relevant patent (5,359,347) from 1994.
> -Rusty
> Ben Swartzlander wrote:
>> Are you talking about patent 4,197,590? That one appears to have been 
>> issued in 1980. It must have expired 10 years ago!
>> -Ben Swartzlander
>> Marco wrote:
>>> Ben Swartzlander escreveu:
>>>> As far as I can tell, X does not support mouse cursors that invert 
>>>> the pixels underneath them (like Windows mouse cursors). This 
>>>> causes a number of problems. First, it makes it impossible to use a 
>>>> 1-pixel wide "I" style cursor for text editing, because the cursor 
>>>> will completely disappear over a black background (or a white 
>>>> background, if you use a white cursor). The only usable "I" style 
>>>> cursors I've seen are 3 pixels wide, such as a black "I" with a 
>>>> white outline to prevent it from vanishing. This would not be so 
>>>> bad, but then certain applications like rdesktop (and possibly 
>>>> Wine) need to use actual Windows cursors, so they convert the 
>>>> Windows cursors bitmap to a valid X cursor by discarding most of 
>>>> the data, which in the case of the 1-pixel wide "I" cursor is 
>>>> mostly useless.
>>>> A apologize if this issue has been discussed before but I want to 
>>>> know (1) if there are any extensions or options I can use to fix 
>>>> this behavior (2) if not, is there a good reason why X has this 
>>>> limitation and (3) what can I do to fix this? I am a long time 
>>>> Windows and Linux use and as much as I would like to replace my 
>>>> Windows desktop with Linux, the poor mouse cursor support is one 
>>>> issue holding me back. I'm willing to code an extension to X if 
>>>> that's what it takes (and obviously write the patch for rdesktop) 
>>>> but I'd like to know how others have dealt with this problem and if 
>>>> anyone has some suggestions.
>>>> thanks,
>>>> -Ben Swartzlander
>>> Because It is patented?
>>> <http://www.google.com/search?q=XOR+cursor+patent&ie=utf-8&oe=utf-8&aq=t&rls=org.debian:pt-BR:unofficial&client=iceweasel-a> 
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