Window manager
In Windows and Mac OS X the window manager is tied into the OS. That's not the case for Linux or BSD. Window Maker is the recommended window manager for GNUstep, but a standard feature-set is needed. GNUstep-based applications have additional needs beyond traditional window managers, like handling the dock icon or the menus. Collecting the requirements here will lead to a specification, so any window manager can clearly state whether or not it is GNUstep-compliant.
Backend WM Attributes
Headers/x11/XGServerWindow.h defines
unsigned long flags unsigned long window_style unsigned long window_level unsigned long reserved Pixmap miniaturize_pixmap; // pixmap for miniaturize button Pixmap close_pixmap; // pixmap for close button. Pixmap miniaturize_mask; // miniaturize pixmap mask Pixmap close_mask; // close pixmap mask unsigned long extra_flags;
#define GSWindowStyleAttr (1<<0) #define GSWindowLevelAttr (1<<1) #define GSMiniaturizePixmapAttr (1<<3) #define GSClosePixmapAttr (1<<4) #define GSMiniaturizeMaskAttr (1<<5) #define GSCloseMaskAttr (1<<6) #define GSExtraFlagsAttr (1<<7) #define GSDocumentEditedFlag (1<<0) #define GSWindowWillResizeNotificationsFlag (1<<1) #define GSWindowWillMoveNotificationsFlag (1<<2) #define GSNoApplicationIconFlag (1<<5) #define WMFHideOtherApplications 10 #define WMFHideApplication 12
Window Level
GNUstep needs arbitrary window levels. EWMH defines these two:
_NET_WM_STATE_ABOVE, ATOM _NET_WM_STATE_BELOW, ATOM
The rest depends on the function of a window. To obtain good interoperability between different Desktop Environments, the following layered stacking order is recommended, from the bottom to the top:
- windows of type _NET_WM_TYPE_DESKTOP
- windows having state _NET_WM_STATE_BELOW
- windows not belonging in any other layer
- windows of type _NET_WM_TYPE_DOCK (unless they have state _NET_WM_TYPE_BELOW) and windows having state _NET_WM_STATE_ABOVE
- focused windows having state _NET_WM_STATE_FULLSCREEN
Windows that are transient for another window should be kept above this window.
The window manager may choose to put some windows in different stacking positions, for example to allow the user to bring currently active window to the top and return it back when the window loses focus.
Window Style
Window style is more or less unchanged, except GNUstep want to display edited document: GSDocumentEditedFlag
Window Type
EWMH defines:
_NET_WM_WINDOW_TYPE_DESKTOP, ATOM _NET_WM_WINDOW_TYPE_DOCK, ATOM _NET_WM_WINDOW_TYPE_TOOLBAR, ATOM _NET_WM_WINDOW_TYPE_MENU, ATOM _NET_WM_WINDOW_TYPE_UTILITY, ATOM _NET_WM_WINDOW_TYPE_SPLASH, ATOM _NET_WM_WINDOW_TYPE_DIALOG, ATOM _NET_WM_WINDOW_TYPE_DROPDOWN_MENU, ATOM _NET_WM_WINDOW_TYPE_POPUP_MENU, ATOM _NET_WM_WINDOW_TYPE_TOOLTIP, ATOM _NET_WM_WINDOW_TYPE_NOTIFICATION, ATOM _NET_WM_WINDOW_TYPE_COMBO, ATOM _NET_WM_WINDOW_TYPE_DND, ATOM _NET_WM_WINDOW_TYPE_NORMAL, ATOM
Comments from Yen-Ju Chen: "GNUstep has no such definition and use window level for this purpose. Personally, I wish GNUstep had a better way to tell which window is for which functions, like app icon, floating panel, menu, key window, main window. The window level is not that reliable when people want to do some tricks. It may not match EWMH one-to-one, but it will be useful for various reasons."