Calling driver.switchTo().frame causes java.lang.StringIndexOutOfBoundsException

[Apxdono]

When trying to switch to frame using opera driver implementation i constantly get 'java.lang.StringIndexOutOfBoundsException: String index out of range: -1' at 'com.opera.core.systems.scope.stp.services.ScopeEcmascriptService'. The method ' framePathToIndex(String framePath)' tries to extract the index between square brackets from framePath value ( which is usually something like "frameName[index]" ). But sometimes the value, that is passed to this method has no brackets at all which causes the problem.

Code to reproduce:
@test
public void frameTest() {
WebDriver driver = new OperaDriver();
driver.get("http://www.w3schools.com/tags/tryit.asp?filename=tryhtml_select_multiple");
driver.switchTo().frame("iframeResult");
WebElement we = driver.findElement(By.tagName("select"));
LOG.info(we.getTagName());
LOG.info(we.getAttribute("multiple"));
driver.switchTo().defaultContent();
WebElement body = driver.findElement(By.id("result"));
LOG.info(body.getTagName());
driver.quit();
}

Sys info:
windows 7 x64
opera version: 12.17 build 1863 for x32 platforms (and a couple of older versions)
java 1.7.0_51 x64

selenium-java versions tested 2.37.0 - 2.42.0
opera-driver version 1.5