added options to disable keyboard grabbing

main.cpp

     float r = options->m_red;
     float g = options->m_green;
     float b = options->m_blue;
+    bool keyboard = options->m_keyboard;
     timespec start, time;
     int cx = 0;
     int cy = 0;
         printf( "H=0\n" );
         return err;
     }
-    err = xengine->grabKeyboard();
-    if ( err ) {
-        printf( "X=0\n" );
-        printf( "Y=0\n" );
-        printf( "W=0\n" );
-        printf( "H=0\n" );
-        return err;
+    if ( keyboard ) {
+        err = xengine->grabKeyboard();
+        if ( err ) {
+            printf( "X=0\n" );
+            printf( "Y=0\n" );
+            printf( "W=0\n" );
+            printf( "H=0\n" );
+            return err;
+        }
     }
     clock_gettime( CLOCK_REALTIME, &start );
     while ( running ) {

options.cpp

     m_green = 0;
     m_blue = 0;
     m_gracetime = 0.1;
+    m_keyboard = true;
 }
 
 void slop::Options::printHelp() {
     printf( "Usage: slop [options]\n" );
-    printf( "Print user selected region to stdout.\n" );
+    printf( "Print user selected region to stdout. Pressing keys or right-clicking cancels selection.\n" );
     printf( "\n" );
     printf( "options\n" );
     printf( "    -h, --help                     show this message.\n" );
+    printf( "    -nk, --nokeyboard              don't try to grab the keyboard. This may fix problems with certain window managers.\n" );
     printf( "    -b=INT, --bordersize=INT       set selection rectangle border size.\n" );
     printf( "    -p=INT, --m_padding=INT        set m_padding size for selection.\n" );
     printf( "    -t=INT, --tolerance=INT        if you have a shaky mouse, increasing this value will make slop detect single clicks better. Rather than interpreting your shaky clicks as region selections.\n" );
             if ( err ) {
                 return 1;
             }
-        } else if ( arg == "-h" || arg == "--help" ) {
+        } else if ( matches( arg, "-nk", "--nokeyboard" ) ) {
+            m_keyboard = false;
+        } else if ( matches( arg, "-h", "--help" ) ) {
             printHelp();
             return 2;
         } else {

options.hpp

     float       m_blue;
     std::string m_xdisplay;
     float       m_gracetime;
+    bool        m_keyboard;
 private:
     int         parseInt( std::string arg, int* returnInt );
     int         parseFloat( std::string arg, float* returnFloat );