Can I insert one window inside another? It must be full feature, so that it receives mouse events, can be focused for keyboard input (or disabled to not receive), could be resized and have an ondraw. Can you give an example or describe?
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I would like to draw some sort of window on top of all the other windows. For example, to display some debugging infos (like conky) or things like a timer.
The main thing is that I would like to able to continue using the other windows while using it (the events go through transparently).
I've tried doing it with pygtk, pyqt and others but can't find a way to make it a real overlay with no event capture.
Is there some low-level x11 solution?
I think the Composite-extension-approach will not work when a compositing manager is running (and thus Composite's overlay window is already used).
Since you explicitly mention "no event capture":
The SHAPE extension allows to set some different shapes for a window. Version 1.1 of this extension added the "input" shape. Just setting this to an empty region should pretty much do what you want.
Some concrete example of exactly what I think you ask for can be found in Conky's source code: http://sources.debian.net/src/conky/1.10.3-1/src/x11.cc/?hl=769#L764-L781
Edit: Since you said that you didn't find anything in Gtk (well, PyGtk), here is the function that you need in Gtk: https://developer.gnome.org/gdk3/stable/gdk3-Windows.html#gdk-window-input-shape-combine-region
You might need Composite extension + GetOverlayWindow request:
Version 0.3 of the protocol adds the Composite Overlay Window, which
provides compositing managers with a surface on which to draw without
interference. This window is always above normal windows and is always
below the screen saver window. It is an InputOutput window whose width
and height are the screen dimensions. Its visual is the root visual
and its border width is zero. Attempts to redirect it using the
composite extension are ignored. This window does not appear in the
reply of the QueryTree request. It is also an override redirect
window. These last two features make it invisible to window managers
and other X11 clients. The only way to access the XID of this window
is via the CompositeGetOverlayWindow request. Initially, the Composite
Overlay Window is unmapped.
CompositeGetOverlayWindow returns the XID of the Composite Overlay
Window. If the window has not yet been mapped, it is mapped by this
request. When all clients who have called this request have terminated
their X11 connections the window is unmapped.
Composite managers may render directly to the Composite Overlay
Window, or they may reparent other windows to be children of this
window and render to these. Multiple clients may render to the
Composite Overlay Window, create child windows of it, reshape it, and
redefine its input region, but the specific arbitration rules followed
by these clients is not defined by this specification; these policies
should be defined by the clients themselves.
C api : XCompositeGetOverlayWindow
PyGTK Solution:
I think the composite and shapes X extensions are sufficiently ubiquitous and shall assume here that they are active on your system. Here's PyGtk code for this:
# avoid title bar and standard window minimize, maximize, close buttons
win.set_decorated(False)
# make the window stick above all others (super button will still override it in the z-order, which is fine)
win.set_keep_above(True)
# make events pass through
region = cairo.Region(cairo.RectangleInt(0, 0, 0, 0))
my_window.input_shape_combine_region(region)
win.show_all()
# set the entire window to be semi-transparent, if we like
win.set_opacity(0.2)
Basically what this does is tell Gtk that other than pixel (0,0) the entire window my_window should not be considered part of itself in terms of event propagation. That in turn, according to my current understanding means that when the pointer moves and clicks, the events go to the underlying window under the pointer position, as if my_window was not there.
Caveat:
This does allow your overlay window being the focus window (due to user-solicited window switching or just because it pops up and gets the focus when your application starts). Which means that for example, keyboard events will still undesirably go to it up until the user has clicked through it to make it lose focus in favor of whatever window is under the cursor. I would likely use the approach described here to iron out this aspect.
If there's a different and proper approach for making a portion of the screen "display stuff but not receive events", without building an oddball window like above over it, I'm happy to learn about it.
I assume that one's particular desktop environment (gnome, unity, etc. on linux) may interfere with this solution depending on version and configuration, on some occasions.
It specifically says in the Wayland TODO text file that Wayland doesn't have active grabs for the pointer yet. But if I run Gnome on Wayland, try clicking a menu open and then clicking outside it, the outside click is swallowed as if the pointer was grabbed by the menu window. How does Gnome manage that?
What you are talking about can be done very easily by creating a transparent overlay over the entire screen. In that case, the click events on the transparent region will not propagate to the underlying elements. You can see this in Telegram's image viewer, where it creates a full-screen gray overlay under the image.
But on the compositor side this effect can be achieved in a different way-- by disabling all input events outside the popup rectangle.
I working on Dialog based applications once i right click on the Dialog Title bar a drop down list is coming with two options 1. Move and 2. Alt+F4 close. Once the User Press Move and he can able to drag the window as he desired and I add the On NC Hits Test to stop dragging its stopping normal dragging but it is not working in this particular context can any body help me in fixing this Bug.
When the user use the keyboard interface, he can move a windows with the arrow keys, without using the mouse.
If you want to limit the position of your dialog, process the WM_MOVING message.
Anybody knows where in xorg source code is located copy/paste routine which is bind to left(copy) and middle(paste) mouse buttons?
More datails:
When you select any text in X session by using left mouse button (normal text selection), it is copied to some "clipboard". Next, when you click middle mouse button in any input control/window text is pasted.
Why I need it:
I need it because I want to change this functionality a little. It is very useful comparing to MsWindows Ctrl-c Ctrl-v. Much faster. But it would be even more if under some button we can reach for previous clipboard content. In this case we can replace one text by other like this:
selecting text A
selecting destination text B (in this moment under middle button text A was overwritten by B)
paste text A using SOME button (not middle button)
It's not in the Xorg source code, but in the sources for each X toolkit or application. The X server simply sends the application the mouse button events, which get processed through its event handling to whatever functions they've bound to those buttons. The copy & paste mechanism you describe is a common convention most toolkits & applications have implemented in their own fashions.
You can read much more about this mechanism in the specs under Peer-to-Peer Communication by Means of Selections in the Inter-Client Communication Conventions Manual
I have a MFC dialog based application. User can change the language of the dialog, and I made this by closing existing dialog, and opening another with changed language. The problem is that the effect in the taskbar is that one icon is removed, and another identical is created in its place. If my application's icon is not the last icon in the task bar it will be perceived as it was moved to the end of taskbar icon set.
I want to retain icon's position in the taskbar, and rather to prevent icon flicker at all from happening. How do I do that?
The application must support OS'es from Windows XP to Windows 7.
EDIT: alternative question for which I would accept an answer is how to create an invisible window that is nevertheless shown in the taskbar, and how to forward relevant window messages from that window to my main window?
Make the dialog a child of another outer parent window. The parent can be a dialog or any other kind of window; all it will be providing is the title bar. If the user tries to resize it it will have to forward resizing commands to the dialog, but otherwise you shouldn't need to do much in the parent window.
Why not replace the dialog with a CFormView instead? That way there's a frame window that wraps around the dialog (which is embedded in a form view) and it's the frame window that owns the taskbar icon.
Create an SDI application that displays a CFormView. Display the dialog in the default language (or whatever langauge the user previously chose) on initialization. When the user chooses the 'change language' option, simply change the form view that's being displayed with a new one.
Bonus feature: with this design, the framework will take care of things like language-specific accelerators and menus for you with no effort on your part.
For more on how to do this, check out http://www.codeguru.com/cpp/w-d/doc_view/viewmanagement/article.php/c3341/Multiple-Views-Using-SDI.htm