README revision 154daed1
1154daed1SmrgThe core protocol interpretation of keyboard modifiers does not include direct 2154daed1Smrgsupport for multiple keyboard groups, so XKB reports the effective keyboard 3154daed1Smrggroup to XKB-aware clients using some of reserved bits in the state field of 4154daed1Smrgsome core protocol events. This modified state field would not be interpreted 5154daed1Smrgcorrectly by XKB-unaware clients, so XKB provides a group compatibility mapping 6154daed1Smrgwhich remaps the keyboard group into a core modifier mask that has similar 7154daed1Smrgeffects, when possible. 8154daed1Smrg 9154daed1SmrgXKB maintains three compatibility state components that are used to make 10154daed1SmrgXKB-unaware clients(*) work as well as possible: 11154daed1Smrg- The compatibility state which corresponds to the effective modifier and 12154daed1Smrg effective group state. 13154daed1Smrg- The compatibility lookup state which is the core-protocol equivalent of the 14154daed1Smrg lookup state. 15154daed1Smrg- The compatibility grab state which is the nearest core-protocol equivalent 16154daed1Smrg of the grab state. 17154daed1Smrg 18154daed1SmrgCompatibility state are essentially the corresponding XKB states, but with 19154daed1Smrgkeyboard group possibly encoded as one or more modifiers. 20154daed1Smrg 21154daed1SmrgModifiers that correspond to each keyboard group are described in this 22154daed1Smrggroup compatibility map. 23154daed1Smrg 24154daed1Smrg 25154daed1Smrg---- 26154daed1Smrg(*) The implementation of XKB invisibly extends the X library to use the 27154daed1Smrgkeyboard extension if it is present. That means, clients that use library or 28154daed1Smrgtoolkit routines to interpret keyboard events automatically use all of XKB 29154daed1Smrgfeatures; clients that directly interpret the state field of core protocol 30154daed1Smrgevents or the keymap direcly may be affected by some of the XKB differences. 31154daed1SmrgThus most clients can take all advantages without modification but it also 32154daed1Smrgmeans that XKB state can be reported to clients that have not explicitly 33154daed1Smrgrequested the keyboard extension. 34