(svn r23791) -Fix [FS#4960]: resize text panel for parameter description if it doesn't fit in 4 lines.

If you resize the window so it's smaller than default the text might still not fit

src/gfx.cpp

@@ -821,6 +821,36 @@ Dimension GetStringMultiLineBoundingBox(StringID str, const Dimension &suggestio
 	return box;
 }
 
+
+/**
+ * Calculates height of string (in pixels). The string is changed to a multiline string if needed.
+ * @param str string to check
+ * @param maxw maximum string width
+ * @return height of pixels of string when it is drawn
+ */
+int GetStringHeight(const char *str, int maxw)
+{
+	char buffer[DRAW_STRING_BUFFER];
+
+	strecpy(buffer, str, lastof(buffer));
+
+	uint32 tmp = FormatStringLinebreaks(buffer, lastof(buffer), maxw);
+
+	return GetMultilineStringHeight(buffer, GB(tmp, 0, 16), FS_NORMAL);
+}
+
+/**
+ * Calculate string bounding box for multi-line strings.
+ * @param str        String to check.
+ * @param suggestion Suggested bounding box.
+ * @return Bounding box for the multi-line string, may be bigger than \a suggestion.
+ */
+Dimension GetStringMultiLineBoundingBox(const char *str, const Dimension &suggestion)
+{
+	Dimension box = {suggestion.width, GetStringHeight(str, suggestion.width)};
+	return box;
+}
+
 /**
  * Draw string, possibly over multiple lines.
  *