Fix clicking TAStudio column header with non-contiguous rows selected

Author: YoshiRulz

src/BizHawk.Client.EmuHawk/tools/TAStudio/TAStudio.ListView.cs

@@ -389,18 +389,36 @@ private void TasView_ColumnClick(object sender, InputRoll.ColumnClickEventArgs e
 						if (ModifierKeys != Keys.Alt)
 						{
 							// nifty taseditor logic
+							// your TAS Editor logic failed us (it didn't account for non-contiguous `SelectedRows`) --yoshi
 							var selection = TasView.SelectedRows.ToArray(); // sorted asc, length >= 1
-							bool allPressed = true;
-							foreach (var index in selection)
+							var allPressed = selection.All(index => CurrentTasMovie.BoolIsPressed(index, buttonName))
+								&& selection[selection.Length - 1] != CurrentTasMovie.FrameCount; // last movie frame can't have input, but can be selected
+							var iSelection = 0;
+							var lastFrameIndexSeen = selection[iSelection] - 1;
+							while (iSelection < selection.Length)
+							{
+								var index = selection[iSelection];
+								if (index - lastFrameIndexSeen is not 1) break;
+								lastFrameIndexSeen = index;
+								iSelection++;
+							}
+							// `iSelection` now points to the element after the last of the first contiguous block--if the whole selection is contiguous, it's pointing after the end of the array...
+							CurrentTasMovie.SetBoolStates(frame: selection[0], count: iSelection, buttonName, val: !allPressed);
+							var blockStart = iSelection;
+							lastFrameIndexSeen = selection[iSelection] - 1;
+							while (iSelection < selection.Length) // ...and these will be equal, so the loop will end immediately
 							{
-								if (index == CurrentTasMovie.FrameCount // last movie frame can't have input, but can be selected
-									|| !CurrentTasMovie.BoolIsPressed(index, buttonName))
+								var index = selection[iSelection];
+								if (index - lastFrameIndexSeen is not 1)
 								{
-									allPressed = false;
-									break;
+									// discontinuity; split off another block, and this is now the start of the next block
+									CurrentTasMovie.SetBoolStates(frame: selection[blockStart], count: iSelection - blockStart, buttonName, val: !allPressed);
+									blockStart = iSelection;
 								}
+								lastFrameIndexSeen = index;
+								iSelection++;
 							}
-							CurrentTasMovie.SetBoolStates(frame: selection[0], count: selection.Length, buttonName, val: !allPressed);
+							CurrentTasMovie.SetBoolStates(frame: selection[blockStart], count: iSelection - blockStart, buttonName, val: !allPressed); // `count` arg will be 0 if the whole selection is contiguous
 						}
 						else
 						{