Fix corrupted text in poorman slider

UpdateText must return a pointer to a fixed buffer, whcih BString.String
isn't, if the sctring is modified.

Copy the data to a char* we can use as a fixed position buffer.

src/apps/poorman/StatusSlider.cpp

@@ -25,5 +25,6 @@ StatusSlider::UpdateText() const
 {
 	fStr.Truncate(0);
 	fFormat.Format(fStr, Value());
-	return fStr.String();
+	strcpy(fPattern, fStr.String());
+	return fPattern;
 }

src/apps/poorman/StatusSlider.h

@@ -27,6 +27,7 @@ public:
 	virtual const char*	UpdateText() const;
 
 private:
+	mutable char			fPattern[256];
 	BMessageFormat			fFormat;
 	mutable	BString			fStr;
 };