title: WPF - How to change children's style on mouseover of parent
body: <p>I have a <code>StackPanel</code> (1), with another <code>StackPanel</code> (2) inside. </p>
  
  <p>SP 2 should be hidden (Opacity:0) until SP 1 is hovered. The mouse-over should change the style of SP2 to Opacity:100. </p>
  
  <p><img src="https://i.stack.imgur.com/AppXZ.jpg" alt="enter image description here"></p>
  
  <p>I've tried defining styles in the StackPanel resources, and using triggers there to then target the inside panel, but I'm not sure how I should be targeting the children from inside the trigger. </p>
  
  <p>What would be a simple style structure to do this?</p>