I propose horizontal movement. No, it should be configurable. Perhaps environment variable or a rc file (of GTK?). Environment variable would be better as a quick standard. setenv KNOBS_CONTROLLED_HORIZONTALLY setenv KNOBS_CONTROLLED_VERTICALLY unsetenv KNOBS_CONTROLLED_HORIZONTALLY unsetenv KNOBS_CONTROLLED_VERTICALLY #include <stdlib.h> if (getenv("KNOBS_CONTROLLED_HORIZONTALLY") != NULL) { // Horizontal movement. } if (getenv("KNOBS_CONTROLLED_VERTICALLY") != NULL) { // Vertical movement. } Juhana