add ability to set parent window when creating windows

src/api/x11/window.rs

@@ -392,12 +392,17 @@ impl Window {
             },
         };
 
+        // getting the parent window
+        let parent = if builder.parent.is_null() {
+                         unsafe { (display.xlib.XDefaultRootWindow)(display.display) }
+        } else {
+            builder.parent as ffi::Window
+        };
         // getting the root window
-        let root = unsafe { (display.xlib.XDefaultRootWindow)(display.display) };
 
         // creating the color map
         let cmap = unsafe {
-            let cmap = (display.xlib.XCreateColormap)(display.display, root,
+            let cmap = (display.xlib.XCreateColormap)(display.display, parent,
                                                       visual_infos.visual as *mut _,
                                                       ffi::AllocNone);
             // TODO: error checking?
@@ -420,7 +425,7 @@ impl Window {
             swa
         };
 
-        let mut window_attributes = ffi::CWBorderPixel | ffi::CWColormap | ffi::CWEventMask;
+        let mut window_attributes = ffi::CWBorderPixel | ffi::CWEventMask | ffi::CWColormap;
 
         if builder.transparent {
             window_attributes |= ffi::CWBackPixel;
@@ -438,7 +443,7 @@ impl Window {
 
         // finally creating the window
         let window = unsafe {
-            let win = (display.xlib.XCreateWindow)(display.display, root, 0, 0, dimensions.0 as libc::c_uint,
+            let win = (display.xlib.XCreateWindow)(display.display, parent, 0, 0, dimensions.0 as libc::c_uint,
                 dimensions.1 as libc::c_uint, 0, visual_infos.depth, ffi::InputOutput as libc::c_uint,
                 visual_infos.visual as *mut _, window_attributes,
                 &mut set_win_attr);

src/lib.rs

@@ -61,7 +61,7 @@ extern crate x11_dl;
 pub use events::*;
 pub use headless::{HeadlessRendererBuilder, HeadlessContext};
 #[cfg(feature = "window")]
-pub use window::{WindowBuilder, Window, WindowProxy, PollEventsIterator, WaitEventsIterator};
+pub use window::{WindowBuilder, Window, WindowID, WindowProxy, PollEventsIterator, WaitEventsIterator};
 #[cfg(feature = "window")]
 pub use window::{AvailableMonitorsIter, MonitorID, get_available_monitors, get_primary_monitor};
 #[cfg(feature = "window")]
@@ -381,7 +381,8 @@ pub struct BuilderAttribs<'a> {
     srgb: Option<bool>,
     transparent: bool,
     decorations: bool,
-    multitouch: bool
+    multitouch: bool,
+    parent: *mut libc::c_void,
 }
 
 impl BuilderAttribs<'static> {
@@ -408,7 +409,8 @@ impl BuilderAttribs<'static> {
             srgb: None,
             transparent: false,
             decorations: true,
-            multitouch: false
+            multitouch: false,
+            parent: std::ptr::null_mut(),
         }
     }
 }
@@ -440,7 +442,8 @@ impl<'a> BuilderAttribs<'a> {
             srgb: self.srgb,
             transparent: self.transparent,
             decorations: self.decorations,
-            multitouch: self.multitouch
+            multitouch: self.multitouch,
+            parent: self.parent,
         };
 
         (new_attribs, sharing)

src/window.rs

@@ -163,6 +163,12 @@ impl<'a> WindowBuilder<'a> {
         self
     }
 
+    /// Sets the parent window
+    pub fn with_parent(mut self, parent: WindowID) -> WindowBuilder<'a> {
+        self.attribs.parent = parent;
+        self
+    }
+
     /// Builds the window.
     ///
     /// Error should be very rare and only occur in case of permission denied, incompatible system,
@@ -609,3 +615,7 @@ impl MonitorID {
         id.get_dimensions()
     }
 }
+
+
+/// Identifier for a display system window.
+pub type WindowID = *mut libc::c_void;