Fixed a case where slop couldn't grab the mouse due to the window manager already having it grabbed due to a key combination being pressed. Slop simply waits for the duration of --gracetime in order for the key combination to be released, thus freeing up the mouse.

CMakeLists.txt

 project( "slop" )
 set( slop_VERSION_MAJOR 4 )
 set( slop_VERSION_MINOR 1 )
-set( slop_VERSION_PATCH 15 )
+set( slop_VERSION_PATCH 16 )
 
 set( BIN_TARGET     "${PROJECT_NAME}" )
 if( NOT CMAKE_INSTALL_PREFIX )

README.md

 help
 ----
 ```text
-slop v4.1.15
+slop v4.1.16
 
 Copyright (C) 2014 Dalton Nell, Slop Contributors
 (https://github.com/naelstrof/slop/graphs/contributors)

src/main.cpp

         fprintf( stderr, "  Try updating X and making sure you have XExtensions installed. (/usr/lib/libXext.so, /usr/include/X11/extensions/shape.h)\n" );
         return EXIT_FAILURE;
     }
-    err = xengine->grabCursor( slop::Cross );
+    err = xengine->grabCursor( slop::Cross, gracetime );
     if ( err != EXIT_SUCCESS ) {
         printSelection( format, true, 0, 0, 0, 0, None );
         return EXIT_FAILURE;

src/x.cpp

 }
 
 // Grabs the cursor, be wary that setCursor changes the mouse masks.
-int slop::XEngine::grabCursor( slop::CursorType type ) {
+// waittime is how long grabCursor can repeatedly try to grab the cursor, if it fails to grab.
+// This is because tiling window managers like i3 grab the mouse while holding down certain keys,
+// while these certain keys also launch slop.
+int slop::XEngine::grabCursor( slop::CursorType type, double waittime ) {
     if ( !m_good ) {
         return EXIT_FAILURE;
     }
     int err = XGrabPointer( m_display, m_root, True,
                             PointerMotionMask | ButtonPressMask | ButtonReleaseMask | EnterWindowMask,
                             GrabModeAsync, GrabModeAsync, None, xfontcursor, CurrentTime );
+    double accumulationtime = 0;
+    int timestep = 10000; // in microseconds
+    while ( err != GrabSuccess && accumulationtime < waittime ) {
+        err = XGrabPointer( m_display, m_root, True,
+                            PointerMotionMask | ButtonPressMask | ButtonReleaseMask | EnterWindowMask,
+                            GrabModeAsync, GrabModeAsync, None, xfontcursor, CurrentTime );
+        usleep( timestep );
+        accumulationtime += double( timestep/1000000.f );
+    }
     if ( err != GrabSuccess ) {
         fprintf( stderr, "Error: Failed to grab X cursor.\n" );
+        switch( err ) {
+            case 1:
+                fprintf( stderr, "       The cursor is already grabbed by another application.\n" );
+                break;
+            case 2:
+                fprintf( stderr, "       The cursor grab was initiated at an invalid time (in the past?) .\n" );
+                break;
+            case 3:
+                fprintf( stderr, "       The cursor is not viewable or outside of the bounds of the root window.\n" );
+                break;
+            case 4:
+                fprintf( stderr, "       The grab is frozen already by an active grab by another application.\n" );
+                break;
+            default:
+                break;
+        }
         fprintf( stderr, "       This can be caused by launching slop weirdly.\n" );
         return EXIT_FAILURE;
     }

src/x.hpp

                         ~XEngine();
     int                 init( std::string display );
     void                tick();
-    int                 grabCursor( slop::CursorType type );
+    int                 grabCursor( slop::CursorType type, double waittime );
     int                 grabKeyboard();
     bool                anyKeyPressed();
     bool                keyPressed( KeySym key );