This is really annoying, and started happening several updates ago (I'm on the latest).
When I have search results from the Find box highlighted in yellow in the file, clicking somewhere else then clicking onto one of the highlighted results will cause the entire result to be selected, and if I'm trying to highlight a part of it for selection, it ends up dragging the whole selection around, or if I type after clicking it, the text is overwritten.
I don't see any reason to auto-select the whole search result when clicking on any part of it. It didn't used to work this way before; things were just fine in this regard before. Every other editor I use, clicking on a found search result just puts the cursor where I clicked between the characters I clicked between.
Is this an instance of the editor being too helpful? Or is this a bug? I can't imagine any JetBrains developers enjoys this weird feature which requires me to click twice into a found result to edit its text or being selecting a part of it as with any other text.