Fix exec icon location and bring it into XDG compliance

diff --git a/src/kmplayervdr.cpp b/src/kmplayervdr.cpp
index 287ce53..09d18a4 100644
--- a/src/kmplayervdr.cpp
+++ b/src/kmplayervdr.cpp
@@ -251,7 +251,7 @@
     DEF_ACT (act_green, i18n ("VDR Key Green"), "green", , TQT_SLOT (keyGreen ()), "vdr_key_green");
     DEF_ACT (act_yellow, i18n ("VDR Key Yellow"), "yellow", , TQT_SLOT (keyYellow ()), "vdr_key_yellow");
     DEF_ACT (act_blue, i18n ("VDR Key Blue"), "blue", , TQT_SLOT (keyBlue ()), "vdr_key_blue");
-    DEF_ACT (act_custom, "VDR Custom Command", "exec", , TQT_SLOT (customCmd ()), "vdr_key_custom");
+    DEF_ACT (act_custom, "VDR Custom Command", "application-x-executable", , TQT_SLOT (customCmd ()), "vdr_key_custom");
     m_app->initMenu (); // update menu and toolbar
     DEF_ACT (act_0, i18n ("VDR Key 0"), "0", TQt::Key_0, TQT_SLOT (key0 ()), "vdr_key_0");
     DEF_ACT (act_1, i18n ("VDR Key 1"), "1", TQt::Key_1, TQT_SLOT (key1 ()), "vdr_key_1");