diff --git a/sysdata.go b/sysdata.go
index 5076093..fe4bb00 100644
--- a/sysdata.go
+++ b/sysdata.go
@@ -2,10 +2,6 @@
 
 package ui
 
-import (
-	"runtime"
-)
-
 const eventbufsiz = 100		// suggested by skelterjohn
 
 // newEvent returns a new channel suitable for listening for events.
@@ -22,63 +18,29 @@ type cSysData struct {
 	alternate	bool			// editable for Combobox, multi-select for listbox, password for lineedit
 	handler	AreaHandler	// for Areas
 }
-func (c *cSysData) make(initText string, window *sysData) error {
-	panic(runtime.GOOS + " sysData does not define make()")
-}
-func (c *cSysData) firstShow() error {
-	panic(runtime.GOOS + " sysData does not define firstShow()")
-}
-func (c *cSysData) show() {
-	panic(runtime.GOOS + " sysData does not define show()")
-}
-func (c *cSysData) hide() {
-	panic(runtime.GOOS + " sysData does not define hide()")
-}
-func (c *cSysData) setText(text string) {
-	panic(runtime.GOOS + " sysData does not define setText()")
-}
-func (c *cSysData) setRect(x int, y int, width int, height int, winheight int) error {
-	panic(runtime.GOOS + " sysData does not define setRect()")
-}
-func (c *cSysData) isChecked() bool {
-	panic(runtime.GOOS + " sysData does not define isChecked()")
-}
-func (c *cSysData) text() string {
-	panic(runtime.GOOS + " sysData does not define text()")
-}
-func (c *cSysData) append(string) {
-	panic(runtime.GOOS + " sysData does not define append()")
-}
-func (c *cSysData) insertBefore(string, int) {
-	panic(runtime.GOOS + " sysData does not define insertBefore()")
-}
-func (c *cSysData) selectedIndex() int {
-	panic(runtime.GOOS + " sysData does not define selectedIndex()")
-}
-func (c *cSysData) selectedIndices() []int {
-	panic(runtime.GOOS + " sysData does not define selectedIndices()")
-}
-func (c *cSysData) selectedTexts() []string {
-	panic(runtime.GOOS + " sysData does not define selectedIndex()")
-}
-func (c *cSysData) setWindowSize(int, int) error {
-	panic(runtime.GOOS + " sysData does not define setWindowSize()")
-}
-func (c *cSysData) delete(int) {
-	panic(runtime.GOOS + " sysData does not define delete()")
-}
-func (c *cSysData) preferredSize() (int, int) {
-	panic(runtime.GOOS + " sysData does not define preferredSize()")
-}
-func (c *cSysData) setProgress(int) {
-	panic(runtime.GOOS + " sysData does not define setProgress()")
-}
-func (c *cSysData) len() int {
-	panic(runtime.GOOS + " sysData does not define len()")
-}
-func (c *cSysData) setAreaSize(int, int) {
-	panic(runtime.GOOS + " sysData does not define setAreaSize()")
-}
+
+// this interface is used to make sure all sysDatas are synced
+var _xSysData interface {
+	make(initText string, window *sysData) error
+	firstShow() error
+	show()
+	hide()
+	setText(text string)
+	setRect(x int, y int, width int, height int, winheight int) error
+	isChecked() bool
+	text() string
+	append(string)
+	insertBefore(string, int)
+	selectedIndex() int
+	selectedIndices() []int
+	selectedTexts() []string
+	setWindowSize(int, int) error
+	delete(int)
+	preferredSize() (int, int)
+	setProgress(int)
+	len() int
+	setAreaSize(int, int)
+} = &sysData{}		// this line will error if there's an inconsistency
 
 // signal sends the event signal. This raise is done asynchronously to avoid deadlocking the UI task.
 // Thanks skelterjohn for this techinque: if we can't queue any more events, drop them